JP2004536492A - Method for providing data services for a large number of small data files - Google Patents

Abstract

【Task】
An apparatus for acquiring a data file that is repeatedly broadcast over at least a first time interval and a second time interval, the file being provided by a user that selects at least one of the broadcast data files. Initiating means for receiving a request (step 303) and an authorized file acquisition process (steps 306, 308) for acquiring at least a first portion of a data file broadcast during a first time interval. Means for displaying at least a portion of the first portion of the data file during at least a portion of the second time interval (step 310), and broadcasting during the second time interval. Means for obtaining a second portion of the data file to be processed, and means for displaying at least a portion of the second portion of the data file. , Apparatus.

Description

【００２５】
図５は、本発明の一実施形態に従って、ＤＯＤ放送システム５０を示す図である。ＤＯＤ放送サーバ２００は、多数の小さいデータファイル（カラオケファイルなど）を含むＲＦ信号を多数の受信ＳＴＢ１００に、放送の伝送媒体５２を介して伝送する。一実施形態では、伝送媒体５２は、既存のケーブルテレビプロバイダによって用いられているようなケーブルテレビ伝送媒体である。従来のＤＯＤ放送システムと異なり、すべての受信ＳＴＢ１００が、伝送されたデータファイルすべてを受信する。ユーザのＳＴＢは、選択されたデータファイルを視聴または格納するために、適切な許可を有する必要がある。
【００２６】
図６は、本発明の一実施形態に従って、高機能ＳＴＢ装置１００を示す簡略化した動作ブロック図である。ＳＴＢ１００は、ＱＡＭデモジュレータ１０２と、ＣＰＵ１０４と、ローカルメモリ１０８と、バッファメモリ１１０と、映像および音声をデコードできるデコーダ１１２と、グラフィクスオーバーレイモジュール１１４と、ユーザインターフェース１１８と、通信回線１２０と、図に示すようにこれらの装置を接続する高速データバス１２２と、を備える。ＣＰＵ１０４は、高機能ＳＴＢ１００の動作全体を制御することで、クライアントの要求に応じてデータを選択し、選択されたデータをデコードし、デコードされたデータを解凍し、デコードされたデータを再アセンブルし、デコードされたデータをローカルメモリ１０８またはバッファメモリ１１０に格納し、格納されたデータをデコーダ１１２に送信する。代表的な実施形態では、ローカルメモリ１０８は、不揮発性メモリ（例えば、ハードドライブ）とセキュアメモリ（例えば、ＲＯＭチップ）の両方を備え、バッファメモリ１１０は、揮発性メモリを備える。
【００２７】
一実施形態では、ＱＡＭデモジュレータ１０２は、送信および受信モジュールと、以下に示す要素の内の少なくとも１つとを備える：プライバシ暗号化／復号化モジュール、前進型誤り訂正デコーダ／エンコーダ、チューナ制御部、ダウンストリームおよびアップストリームプロセッサ、ＣＰＵ、および、メモリインターフェース回路。ＱＡＭデモジュレータ１０２は、変調ＩＦ信号を受信し、信号をサンプリングおよび復調してデータを復元する。
【００２８】
代表的な実施形態では、アクセスが許可されると、デコーダ１１２は、選択されたデータファイルのデータブロックをデコードして、出力装置１２４上で表示可能な画像にする。デコーダ１１２は、再生、停止、一時停止、コマ送り、巻き戻し、早送りなど、加入クライアントからのコマンドをサポートしている。デコーダ１１２は、デコードされたデータをグラフィクスオーバーレイモジュール１１４に提供する。グラフィクスオーバーレイモジュール１１４は、例えば、アルファ・ブレンディングまたはピクチャ・イン・ピクチャ機能によって、表示されたグラフィクスの質を向上させる。グラフィクスオーバーレイモジュールは、次いで、品質を向上された表示信号を、ユーザに表示するために、出力装置１２４に提供する。代表的な実施形態において、グラフィクスオーバーレイモジュール１１４は、例えば、サービスプロバイダが、本発明に従ったシステムを用いてゲーム・オン・デマンドサービスを提供する場合には、ゲームプレイングモード中にグラフィクスを加速させるために用いることもできる。出力装置１２４は、テレビ、コンピュータ、任意の適切なディスプレイモニタ、ＶＣＲなど、任意の適切な装置でよい。
【００２９】
ユーザインターフェース１１８は、ユーザによるＳＴＢ１００の制御を実現するものであり、リモートコントロール装置、キーボードなど、任意の適切な装置であってよい。通信回線１２０は、さらなる通信接続を提供する。これは、別のコンピュータに接続されてもよいし、双方向通信を実施するために用いられてもよい。データバス１２２は、本発明に必要とされるリアルタイムでのデータ通信を実行するのに適した市販の「高速」データバスが好ましい。適切な例としては、ＵＳＢ、ファイヤワイヤなどが挙げられる。サービスは、すべてのケーブルテレビ加入者に対して放送されるが、選択されたＤＯＤサービスの視聴を許可されたＳＴＢ１００を持っているＤＯＤ加入者だけが、その選択されたサービスをデコードして利用できる。
【００３０】
一実施形態では、高機能ＳＴＢ１００は、選択されたデータファイルのダウンロードが完了する前に、そのファイルの再生を開始することができる。このプロセスについては、図８を参照して、より詳しく説明する。
【００３１】
図７は、本発明の一実施形態に従って、１以上の小さなデータファイル（カラオケファイルなど）を注文するためのプロセス３００を示している。プロセス３００は、ＳＴＢ１００（図５）が、ＥＰＧプログラムをＤＯＤ放送サーバ２００（図５）から受信する工程３０２に始まる。ＥＰＧプログラムは、ＤＯＤサーバから利用できるすべてのファイルを列挙している。工程３０３において、ユーザは、所望のタイトルの各々に関連付けられたボタンを押すことにより、ＥＰＧから１以上のタイトルを選択する。工程３０６において、ＳＴＢは、ユーザが、選択されたデータファイルの視聴を許可されているか否かを判断する。この工程は、ＳＴＢ１００（図５）に格納された値を確認する工程と、これらの値を、各々の選択されたデータファイルに必要な加入レベルと比較する工程と、を含んでよい。かかる認証方法は、２００１年７月９日に出願されたＫｈｏｉ Ｈｏａｎｇの特許出願「CONTROLLING DATA-ON-DEMAND CLIENT ACCESS」、出願番号０９／９０２，５０３、に記載されている。選択されたデータファイルへのアクセスを認証する他の方法は、ＤＯＤサーバ２００（図５）またはその他のリモートサイトとの双方向通信を含んでもよい。
【００３２】
ユーザが、選択されたデータファイルの視聴を許可される（工程３０８）場合には、プロセスは、工程３０９に進む。工程３０９において、ＳＴＢは、選択されたファイルの格納を開始する。工程３１０において、ＳＴＢは、ユーザが視聴できるように、選択されたタイトルを再生する。
【００３３】
ユーザが、選択されたデータファイルの視聴を許可されない（工程３０８）場合には、ＳＴＢは、工程３１２において、アクセスを拒否する旨のメッセージを表示する。ＳＴＢは、さらに、ユーザが、拒否されたサービスにアクセスできる方法を指示するメッセージを表示してもよい。
【００３４】
図７Ａは、選択されたＤＯＤサービスを購入するための別の双方向認証プロセス３５０を示している。プロセス３５０は、ＳＴＢ１００（図５）が、ＥＰＧプログラムをＤＯＤ放送サーバ２００（図５）から受信する工程３５２に始まる。ＥＰＧプログラムは、ＤＯＤサーバから利用できるすべてのファイルを列挙している。工程３５３において、ユーザは、所望のタイトルに関連付けられた購入ボタンを押すことにより、ＥＰＧからタイトルを選択する。工程３５４において、ＳＴＢは、所望の選択を視聴する許可に対する要求をサーバ２００（図５）に送る。この要求は、電話モデムまたは上り回線を介してサーバ２００に伝送される。
【００３５】
工程３５６において、サーバ２００は、選択されたタイトルの許可を要求ＳＴＢに送ると共に、ユーザの勘定を記録することにより請求システムを更新する。許可は、モデムとダウンストリームのいずれかを介して伝送媒体５２（図５）に送られる。工程３５８において、ＳＴＢは、許可を受信して、要求されたタイトルの格納を開始する。工程３６０において、ＳＴＢは、ユーザが視聴できるように、選択されたタイトルを再生する。
【００３６】
図８は、カラオケファイルのような２つの別個の小さいデータファイル４００の放送の一例を示す図である。この例では、２つのタイトルが、同じチャンネルの２つの別個の帯域幅を通して、繰り返し放送されている。第１のタイトル４０２（タイトル１）は、２分の再生時間を有しており、ダウンロードに１分を要する。第２のタイトル４０４（タイトル２）は、４分の再生時間を有しており、ダウンロードに２分を要する。各タイトルは、自身の割り当て帯域幅を介して同時に繰り返し放送される。
【００３７】
所望のタイトル（例えば、タイトル１およびタイトル２）が選択されると（図７の工程３０３）、ＳＴＢ１００は、タイトル１およびタイトル２両方のダウンロードを開始し、１分後に、タイトル１の再生を開始する。ＳＴＢ１００がタイトル１の再生を開始する時点では、ＳＴＢ１００は、タイトル２をダウンロードし続けており、そのダウンロードには、さらに１分の時間を要する。タイトル１の再生が終了すると、ＳＴＢ１００は、タイトル２の再生を開始する。
【００３８】
ＳＴＢ１００は、あるタイトルに関する１つの伝送の終わり部分と、その同一タイトルに関する次に繰り返された伝送の開始部分とを用いて、データブロックをアセンブルすることにより、常に最小限の時間で各々の選択をダウンロードすることができる。かかるプロセスは、２０００年１０月２５日に出願されたＫｈｏｉ Ｈｏａｎｇの特許出願「METHOD AND APPARATUS FOR TRANSMITTING NON-VOD SERVICES」、代理人整理番号６０５９５−３０１８０１、に記載されており、これは、引用によって本願に組み込まれる。各ファイルに別個の伝送帯域幅が割り当てられているため、ＳＴＢは、複数のファイルを同時にダウンロードすることもできる。
【００３９】
好ましい実施形態では、ＳＴＢ１００は、ファイルを再生するビットレートよりも大きいビットレートでファイルをダウンロードすることができる。本実施形態では、伝送されるデータファイルは、選択されたタイトルに関連するデータを含むデータブロックのシーケンスからなる。ＳＴＢは、選択されたタイトルに対応するシーケンスの第１のデータブロックを受信するとすぐに、選択されたタイトルの再生を開始することができる。タイトルの円滑な表示を実現するためには、ＳＴＢは、タイトルがユーザに対して再生されるよりも速く、選択されたタイトルのデータブロックをダウンロードできなければならない。一実施形態では、ＳＴＢは、予想ダウンロード時間を算出して、データファイルの再生を開始できる時間を決定する。この算出は、エンコードビットレート、伝送ビットレート、およびバッファブロックサイズに基づく。ダウンロードは、ファイルの第１のデータブロック以外のデータブロックから開始されてもよいため、待ち時間は、標準的なダウンロード時間よりも長くなる。ＳＴＢが、選択されたファイルの再生を開始してもよい時間は、以下のように算出できる：
【００４０】
Ｔｓ≧Ｔｐ＊（Ｔｄ／Ｔｐ−（ＮＢ−１）／ＮＢ） 式１
【００４１】
ここで、
Ｔｓ：データファイルの再生開始時間
Ｔｐ：データファイルの再生に必要な時間
ＥＢＲ：エンコードビットレート
ＴＢＲ：伝送ビットレート
Ｔｄ：ファイル全体をダウンロードするために必要な時間（Ｔｄ＝ファイルサイズ／伝送ビットレート）
ＮＢ：ファイル内のデータブロック数（ＮＢ＝データファイルサイズ／バッファブロックサイズ）
【００４２】
例えば、バッファブロックサイズが１．５ＭＢである場合には、２Ｍｂ／ｓでエンコードされ、伝送レートが１Ｍｂ／ｓである３分の４５ＭＢファイル（ＮＢ＝３０）は、約１８６秒の待ち時間（Ｔｓ）を有する。Ｔｓ＝３×（２／１−（３０−１）／３０）＝１８６秒。また、バッファブロックサイズが１．５ＭＢである場合に、２Ｍｂ／ｓでエンコードされ、伝送レートが１Ｍｂ／ｓである１分の６ＭＢファイル（ＮＢ＝４）は、約７５秒の待ち時間（Ｔｓ）を有する。Ｔｓ＝１分×（２／１−（４−１）／４）＝７５秒。
【００４３】
図９は、単一の伝送チャンネルの共有帯域幅で、複数の小さいデータファイルを伝送する別の方法を示している。図９は、データブロックのシーケンスが、一例の伝送チャンネルの第１の伝送帯域幅５０２および第２の伝送帯域幅５０４で伝送されている様子を示す。第１の帯域幅は、最初に、第１のカラオケソングに対応するデータブロック５０６の第１のシーケンスを伝送し、次いで、第２のカラオケソングに対応するデータブロック５０８の第２のシーケンスを伝送し、最後に、第３のソング５１０のデータブロックを伝送する。帯域幅５０２は、３つのカラオケソングに関するこのシーケンスの伝送を無制限に繰り返す。第２の伝送帯域幅５０４は、第４のカラオケソング５１２、第５のカラオケソング５１４、第６のカラオケソング５１６、および第７のカラオケソング５１８を伝送する。帯域幅５０４も、このシーケンスを無制限に繰り返す。本発明のこの態様によると、同じ数の割り当てチャンネルで、はるかに多くの小さいデータファイルを利用可能であるものの、より長い待ち時間が必要になる。
【００４４】
図１０は、本発明の一実施形態に従って、デジタルテキスト・オン・デマンド（ＴＯＤ）サービスを受信するためのプロセス６００を示している。プロセス６００は、ＳＴＢ１００（図５）が、ＥＰＧプログラムをＤＯＤ放送サーバ２００（図５）から受信する工程６０２に始まる。ＥＰＧプログラムは、ＤＯＤサーバから利用できるすべてのファイル（本、雑誌、定期刊行物など）を列挙している。ファイルの種類は、映画、デジタルテキストファイル、音楽などを含んでよい。工程６０４において、ユーザは、所望のサービスに関連付けられたリモートコントロールボタンを押すことにより、ＥＰＧから所望のデジタルテキストファイルを選択する。なお、リモートコントロールは、一体型のマウスやローラーボールを含んでよい。工程６０６において、ＳＴＢは、ユーザが、選択されたデジタルテキストファイルの視聴を許可されているか否かを判断する。この工程は、ＳＴＢ１００（図５）に格納された値を確認する工程と、これらの値を、各々の選択されたデジタルテキストファイルに必要な加入レベルと比較する工程と、を含んでよい。かかる認証方法は、２００１年７月９日に出願されたＫｈｏｉ Ｈｏａｎｇの特許出願「CONTROLLING DATA-ON-DEMAND CLIENT ACCESS」、出願番号０９／９０２，５０３、に記載されている。選択されたデジタルテキストファイルへのアクセスを認証する他の方法は、ＤＯＤサーバ２００（図５）またはその他のリモートサイトとの双方向通信を含んでもよい。
【００４５】
ユーザが、選択されたファイルの視聴を許可される（工程６０６）場合には、プロセスは、工程６１０に進む。工程６１０において、ＳＴＢは、選択されたファイルの格納を開始する。工程６１０において、ＳＴＢは、要求されたテキストの格納を開始する。工程６１２において、ＳＴＢは、ユーザに対してテキストを表示する。
【００４６】
一実施形態では、２５０ページ／チャンネル（合計１００，０００ページ）で、４０００もの番組（サービス／複数チャンネル）を、１つの物理チャンネルで伝送することができる。しかしながら、１つの物理チャンネルで伝送する番組の数が大きくなると、それに応じて、所望のサービスにアクセスするための応答時間も長くなる。各番組は、複数のページを含むことができる。より多くのページを含む番組ほど、アクセスに要する時間は長くなる。番組は、各テキストページの内容を説明するページインデックスを含んでもよい。
【００４７】
テキスト／グラフィク表示も可能であるが、大量のデータが必要になり、それに応じて、応答時間も増大する。利用可能なフォーマットとしては、例えば、ＪＰＥＧやビッマップなどが挙げられる。ページは、テキストとグラフィック画像を含んでよい。ページは、さらに、ハイパーテキスト言語（ＨＴＭＬなど）を含んでもよい。
【００４８】
テキストファイルは、新聞、雑誌、書籍、および政府刊行物などの出版物を含んでよい。テキストで利用可能な他の情報は、天気、輸送スケジュール、ホテル情報、株式情報、ショッピング、速報、および第三者による請求サービスを含んでもよい。
【００４９】
図１１は、本発明に従って、表示ページに関するトランザクションを実行するためのプロセス７００を示している。工程７０２において、ＳＴＢは、１以上の対話式トランザクション機能を含むテキストページを受信する。工程７０４において、ＳＴＢは、ユーザに対してページを表示する。トランザクション機能は、表示されたページ上に視覚的に示される。これらの機能は、太字、または、色の違いなどで示されてよい。可能なトランザクション機能としては、第三者業者への支払いを行うためのアイコン、選択された商品やサービスを購入するためのアイコン、政治選挙の投票を行うためのアイコンなどが含まれてよい。例えば、通信販売チャンネルのページは、選択された商品を購入するためのアイコンを有してよい。株式チャンネルのページは、様々な株式、数量または値段を示す買い注文アイコンを有してよい。
【００５０】
工程７０６において、ユーザは、選択されたトランザクション機能を起動する。工程７０８において、ＳＴＢは、選択された機能の内容に対応するメッセージを、選択された機能に相当する組織に相当するロケーションに送信する。例えば、ユーザが、ＩＢＭ社の株式を１００ドルで１００株購入するアイコンをダブルクリックすると、ＳＴＢは、電話モデム、ローカルエリアネットワーク、またはその他の接続を介して、アイコンに関連付けられた株式仲介人のウェブサイトに、その購入を要求するメッセージを送信する。例えば、ユーザが、ガス料金支払いアイコンを選択した場合には、ＳＴＢは、振替を許可するメッセージを適切な公共施設に送信する。
【００５１】
工程７１０において、受信サイトは、送信された特定のメッセージに対応する機能を実行する。例えば、通信販売業者は、注文メッセージに応じて商品を発送する。
【００５２】
上述の例は、本発明の一部の代表的な実施形態を例示したものであり、当業者は、これらから、他の実施形態、変更例、変形例を容易に導くことができる。したがって、本発明は、上述した特定の実施形態に限定されず、添付した特許請求の範囲によって規定される。
【図面の簡単な説明】
【００５３】
【図１】従来技術のＤＯＤシステムを示す簡略化した機能ブロック図。
【図２】従来技術のＳＴＢを示す簡略化した機能ブロック図。
【図３】ネットワークを介したＤＯＤ伝送のための従来の方法を示すブロック図。
【図４】本発明の一実施形態に従って、ＤＯＤ放送サーバを示す簡略化したブロック図。
【図５】本発明の一実施形態に従って、ＤＯＤサーバシステムを示す動作ブロック図。
【図６】本発明の一実施形態に従って、高機能セット・トップ・ボックスを示すブロック図。
【図７】本発明の一実施形態に従って、データファイルをダウンロードするための方法を示すフローチャート。
【図７Ａ】本発明の一実施形態に従って、選択されたＤＯＤサービスを購入するための別の双方向認証プロセスを示す図。
【図８】本発明の一実施形態に従って、データブロック伝送を示す簡略化した図。
【図９】本発明の別の実施形態に従って、データブロック伝送を示す簡略化した図。
【図１０】本発明の一実施形態に従って、テキスト／グラフィックファイルのダウンロード動作を示すフローチャート。
【図１１】本発明の一実施形態に従って、テキスト／グラフィックファイルのトランザクションを示すフローチャート。
【符号の説明】
【００５４】
１０…データ・オン・デマンドシステム
１２…テレビ
１４…セット・トップ・ボックス
１６…広域ネットワーク
１８…ＤＯＤサーバ
２０…ディスクアレイ
２２…トランスポートストリーム・デマルチプレクサ
２４…映像デコーダ
２６…音声デコーダ
２８…クロック制御部
２９…デモジュレータ
５２…データネットワーク
１００…受信ＳＴＢ
１０２…ＱＡＭデモジュレータ
１０４…ＣＰＵ
１０８…ローカルメモリ
１１０…バッファメモリ
１１２…デコーダ
１１４…グラフィクスオーバーレイモジュール
１１８…ユーザインターフェース
１２０…通信回線
１２２…データバス
１２４…出力装置
２００…ＤＯＤサーバ
２０２…中央制御サーバ
２０４…中央ストレージ
２０６…データバス
２１１…チャンネルサーバ
２１２…アップコンバータ
２１４…コンバイナ／アンプリファイア
４００…データファイル
４０２…第１のタイトル
４０４…第２のタイトル
５０２…第１の送信帯域幅
５０４…第２の送信帯域幅
５０６…データブロック
５０８…データブロック
５１０…データブロック
５１２…データブロック
５１４…データブロック
５１６…データブロック
５１８…データブロック【Technical field】
[0001]
The present invention generally relates to data on demand (DOD) broadcast systems. In particular, the present invention relates to a digital DOD system for transmitting multiple small data files to multiple end users.
[Background Art]
[0002]
In the modern information age, there is a need for quick access to all entertainment, news, goods and services. At present, there is no service that can immediately provide a wide variety of small data files, such as karaoke audio / video files, to a large number of individual consumers. Although Internet web pages provide a wealth of text on a variety of topics, they require two-way communication, and existing modem technologies can be time consuming to access. In addition, typical Internet websites can only transmit typical files to a limited number of recipients.
[0003]
Prior Art FIG. 1 shows a simplified prior art functional block diagram of a data on demand (DOD) system 10. The user selects an audio / video service (for example, a karaoke music file) listed on an electronic program guide (EPG) on a display screen such as the television 12, and sets a set-top box (eg, a karaoke music file) connected to the television 12. An order for selecting audio / video is made using the STB) 14. The STB 14 can communicate with the DOD server 18 via a two-way network connection over a wide area network 16 such as the Internet. Upon receiving a request from the user (viewer) 12, the DOD server 18 accesses a bank of the disk array 20 that stores a selection of available audio / video in the EPG, and retrieves the selected audio / video file. Then, the data is transmitted to the user via the wide area network. This exemplary interactive distribution infrastructure 16 may consist of any combination of telephone networks and / or cable television systems. In transmitting the selected file, the video data may be encoded according to any suitable protocol required to maximize overall system efficiency.
[0004]
FIG. 2 relating to the prior art is a simplified functional block diagram of the STB 14 of the prior art. The STB 14 includes a demodulator 29, a transport stream demultiplexer 22, a video decoder 24, an audio decoder 26, and a clock control unit 28. When the user's request is processed by the DOD server, the corresponding data is transmitted to the user's STB. A typical prior art STB 14 may send an input transport stream to a demodulator 20 to demodulate an input signal. The demodulated signal is then split by transport stream demultiplexer 22 into individual components. The video data component of the input stream is decoded by the video decoder 24, and the audio data component is decoded by the audio decoder 26. The input transport stream further provides timing information used by the clock controller 28. Clock controller 28 provides a timing output used to match or synchronize the video data with the corresponding audio data.
[0005]
Prior Art FIG. 3 is a block diagram illustrating a prior art method 40 for DOD transmitting a small data file over a network. In order for a user to make a particular audio / video selection, an EPG containing the available selections and timing must be provided to the user. In step 30, the STB 14 tunes to the appropriate channel and receives the transmitted EPG. Then, in step 32, STB 14 provides the user with an EPG for viewing. At step 34, the user input is transmitted to the DOD server 18 in the form of a request for a particular audio / video selection. The STB 14 then tunes to the appropriate channel or allocated bandwidth to receive the requested data file. In step 38, the data file requested by the client is received by the STB 14 and provided to the client in a displayable image form through demodulation, demultiplexing, and decoding of the input signal. Typically, prior art systems may have a download rate of 2 Mb / s to 6 Mb / s. For DOD files, a download rate that is large enough to realize real-time video playback is required.
[0006]
Usually, a karaoke music file is encoded in an MPEG format (MPEG-1 or MPEG-2), and the bit rate at that time is a CBR (fixed bit rate) of 1.5 Mbs to 4 Mbs or a VBR used in a DVD format or the like. It is. Music playback time varies from one to several minutes. At an encode bit rate of 1.5 Mb / s (MPEG-1), the file length for a 3 minute karaoke song is approximately 34 megabytes, much smaller than most movie or other audio / video files.
[0007]
Current DOD broadcast systems used to transmit many small data files have many limitations. The transmission bandwidth required for a conventional DOD server system is determined by the number of DOD users. That is, as the number of users increases, the required bandwidth increases proportionally. Conventional DOD server systems require two-way communication. Conventional DOD systems cannot play a file at a bit rate higher than the transmission bit rate of the file being downloaded for streaming video.
[0008]
Existing systems require a large amount of bandwidth, which limits the number of clients that can be serviced at one time, mainly due to bandwidth requirements. Furthermore, the prior art transmission methods have not been able to take advantage of the performance and processing power of the new STB, which has the high functionality of downloading files using more flexible and efficient algorithms.
[0009]
Therefore, there is a need for a DOD broadcast system that can simultaneously transmit many small data files to many clients over a narrow bandwidth without the need for two-way communication. In addition, there is a need for a bandwidth efficient method of utilizing the performance of advanced STBs, for example, downloading data files by processing transmitted data using more complex protocols.
DISCLOSURE OF THE INVENTION
[Means for Solving the Problems]
[0010]
The present invention provides a DOD broadcast system capable of transmitting a large number of small data files to a large number of clients simultaneously over a small bandwidth without requiring two-way communication. The present invention further provides an STB capable of downloading a data file at a bit rate higher than the reproduction bit rate of the data file. This makes it possible to download the data file faster than the data file can be reproduced. Furthermore, a bandwidth efficient method of downloading data files by utilizing the performance of advanced STBs, for example, by processing transmitted data using more complex protocols, is provided.
[0011]
Briefly described, one aspect of the present invention is an apparatus for obtaining (retrieving) a plurality of data files that are repeatedly broadcast over at least a first time interval and a second time interval. Means for receiving at least one file request from a user for selecting at least one of the files, and initiating an authorized file retrieval process to broadcast at least one selected file during a first time interval Means for obtaining at least a first portion of the data file; means for displaying at least a portion of the first portion of the at least one data file during at least a portion of the second time interval; Means for obtaining a second portion of the at least one data file broadcast during a second time interval; And means for displaying at least a portion of the second portion of the data file.
[0012]
Another embodiment of the present invention is a method for transmitting a number of small data files to a number of consumers, comprising transmitting a plurality of data files to a plurality of users, the method comprising: Disclosed are methods wherein consumers authorized to receive may perform the reception, and consumers who are not authorized to receive the selected file are barred from receiving. The method comprises transmitting an electronic program guide (EPG) to a plurality of users, and the user may use the electronic program guide to select a selected data file. Each data file is transmitted repeatedly. Further, each data file has an allocated bandwidth, and the data file is repeatedly transmitted at a corresponding bandwidth.
[0013]
In one embodiment of the method, an icon corresponding to each data file is displayed by the EPG, and a user may select a data file by selecting the displayed icon. In another embodiment, at least one of the plurality of data files is a karaoke music file that includes audio and video data.
[0014]
Alternatively, at least one of the plurality of data files is a text file including graphics and a plurality of pages, and at least one page includes text information. The service corresponding to the transaction function included in the text file may be activated by the first user.
BEST MODE FOR CARRYING OUT THE INVENTION
[0015]
The present invention provides a DOD broadcast system capable of transmitting a large number of small data files to a large number of clients simultaneously over a small bandwidth without requiring two-way communication. The present invention further provides an STB capable of downloading a data file at a bit rate higher than the reproduction bit rate of the data file. This makes it possible to download the data file faster than the data file can be reproduced. This is achieved by repeatedly transmitting each small data file to all current consumers with a dedicated allocated bandwidth. Consumers can access any selected data file with only a short delay using a sophisticated STB. Smart STBs further restrict consumers from accessing services that they have not subscribed to. In this way, there is no need to transmit individual files to individual consumers for the purpose of restricting access.
[0016]
FIG. 4 is a simplified block diagram illustrating a transmission server according to one embodiment of the present invention. The DOD server 200 includes a plurality of channel servers 211, a plurality of up-converters 212 respectively corresponding to the channel servers 211, a combiner / amplifier 214, a central control server 202, and a central storage 204. The components are connected via a data bus 206 as shown. As described below, the central control server 202 not only starts real-time transmission when the channel server 211 is ready, but also controls the offline operation of the channel server 211. Central storage 204 typically stores data files in digital format. However, any suitable mass persistent data storage may be used.
[0017]
In an exemplary embodiment, the data files stored in the central storage 204 are over a standard network interface (eg, an Ethernet connection) by any authorized computer, such as a central control server 202 connected to a network. Can be accessed. The channel server 211 provides a data file retrieved (acquired) from the central storage 204 according to an instruction from the central control server 202. The retrieval of digital data and the scheduling of digital data transmission for DOD is performed "off-line", whereby each channel server 211 is fully prepared for real-time data transmission. When each channel server 211 is ready to provide a DOD, it notifies the central control server 202, at which point the central control server 202 can control the channel server 211 to start DOD transmission. .
[0018]
In a preferred embodiment, the central control server 202 includes a graphic user interface (not shown) to allow service providers to schedule data delivery via drag and drop operations. Further, the central control server 202 authenticates and controls the channel server 210 to start or stop according to the distribution queue. A system and method for providing a one-way DOD broadcast matrix is described in a patent application filed May 31, 2000 by Khoi Hoang, entitled "SYSTEMS AND METHODS FOR PROVIDING VIDEO ON DEMAND SERVICES FOR BROADCASTING SYSTEMS", application number 09/584. , 832. This is incorporated herein by reference.
[0019]
Each channel server 211 is assigned to a channel and connected to the upconverter 212. The channel server 211 transmits the DOD information to each up converter 212. The output of each channel server 211 is an intermediate frequency (IF) signal modulated by quadrature amplitude modulation (QAM) having a frequency that is compatible with the corresponding upconverter 212. The QAM modulated IF signal depends on the standard adopted. The standard currently adopted in the United States is the data-over-cable-systems-interface-specification (DOCSIS) standard, which requires an IF frequency of about 43.75 MHz.
[0020]
The up-converter 212 converts the IF signal received from the channel server 211 into a high-frequency signal (RF signal). RF signals include frequency and bandwidth and depend on the desired channel and the standards employed. For example, for cable television channel 80, according to current standards in the United States, RF signals have a frequency of about 559.25 MHz and a bandwidth of about 6 MHz.
[0021]
The output of upconverter 212 is sent to combiner / amplifier 214. The combiner / amplifier 214 amplifies, adjusts, and combines the received RF signal, and outputs the amplified signal to the data network 52 (FIG. 5). According to one embodiment, the data network is a cable television distribution network or other one-way data distribution network.
[0022]
In an exemplary embodiment, 20 broadcast channels are allocated for transmission of karaoke files and other small data files. Usually, a karaoke music file is encoded in an MPEG format (MPEG-1 or MPEG-2), and the bit rate at that time is a CBR (fixed bit rate) of 1.5 Mbs to 4 Mbs or a VBR used in a DVD format or the like. It is. Music playback time varies from one minute to several minutes. At an encoding bit rate of 1.5 Mb / s (MPEG-1), the file length for a 3 minute karaoke song is approximately 34 megabytes.
[0023]
For example, assume that each channel has an available bandwidth of 36 Mbs (for an 8 MHz cable system using QAM64). In that case, each small data file is assigned a transmission bandwidth of 1 Mbs. Accordingly, 36 karaoke files can be transmitted on each channel, and a total of 720 karaoke data files can be transmitted on 20 channels. If the subscriber is allowed access to a typical karaoke file (encoded using MPEG-1 and has a playback time of 3 minutes), the download time will be about 4.5 minutes (( 3 minutes × 1.5 Mbs) / 1 Mbs). The following table shows an example of the relationship between bit rate, allocated bandwidth, number of small data files downloaded, and download time for a typical three minute karaoke song.
[0024]
[Table 1]

[0025]
FIG. 5 is a diagram illustrating a DOD broadcast system 50 according to one embodiment of the present invention. The DOD broadcast server 200 transmits an RF signal including a number of small data files (such as a karaoke file) to a number of receiving STBs 100 via a broadcast transmission medium 52. In one embodiment, transmission medium 52 is a cable television transmission medium such as that used by existing cable television providers. Unlike a conventional DOD broadcasting system, all receiving STBs 100 receive all transmitted data files. The user's STB must have the appropriate permissions to view or store the selected data file.
[0026]
FIG. 6 is a simplified operation block diagram showing the advanced STB device 100 according to one embodiment of the present invention. The STB 100 includes a QAM demodulator 102, a CPU 104, a local memory 108, a buffer memory 110, a decoder 112 capable of decoding video and audio, a graphics overlay module 114, a user interface 118, a communication line 120, A high-speed data bus 122 for connecting these devices as shown. The CPU 104 controls the entire operation of the advanced STB 100 to select data according to a client request, decode the selected data, decompress the decoded data, and reassemble the decoded data. Then, the decoded data is stored in the local memory 108 or the buffer memory 110, and the stored data is transmitted to the decoder 112. In an exemplary embodiment, local memory 108 comprises both non-volatile memory (eg, a hard drive) and secure memory (eg, a ROM chip), and buffer memory 110 comprises volatile memory.
[0027]
In one embodiment, QAM demodulator 102 comprises a transmitting and receiving module and at least one of the following elements: a privacy encryption / decryption module, a forward error correction decoder / encoder, a tuner control, Downstream and upstream processors, CPU, and memory interface circuits. QAM demodulator 102 receives the modulated IF signal and samples and demodulates the signal to recover the data.
[0028]
In an exemplary embodiment, when access is granted, decoder 112 decodes the data blocks of the selected data file into an image that can be displayed on output device 124. The decoder 112 supports commands from the subscribing client, such as play, stop, pause, frame advance, rewind, and fast forward. The decoder 112 provides the decoded data to the graphics overlay module 114. The graphics overlay module 114 enhances the displayed graphics, for example, by alpha blending or picture-in-picture functions. The graphics overlay module then provides the enhanced display signal to the output device 124 for display to the user. In an exemplary embodiment, graphics overlay module 114 accelerates graphics during game playing mode, for example, when a service provider provides a game-on-demand service using a system according to the present invention. Can also be used for Output device 124 may be any suitable device, such as a television, computer, any suitable display monitor, VCR, and the like.
[0029]
The user interface 118 realizes control of the STB 100 by a user, and may be any appropriate device such as a remote control device and a keyboard. Communication line 120 provides an additional communication connection. This may be connected to another computer or used to implement two-way communication. Data bus 122 is preferably a commercially available "high speed" data bus suitable for performing the real-time data communications required by the present invention. Suitable examples include USB, firewire, and the like. The service is broadcast to all cable television subscribers, but only the DOD subscriber having the STB 100 permitted to view the selected DOD service can decode and use the selected service. .
[0030]
In one embodiment, the enhanced STB 100 may start playing the selected data file before the file has been downloaded. This process will be described in more detail with reference to FIG.
[0031]
FIG. 7 illustrates a process 300 for ordering one or more small data files (such as karaoke files), according to one embodiment of the present invention. Process 300 begins at step 302 where STB 100 (FIG. 5) receives an EPG program from DOD broadcast server 200 (FIG. 5). The EPG program lists all files available from the DOD server. At step 303, the user selects one or more titles from the EPG by pressing a button associated with each of the desired titles. In step 306, the STB determines whether the user is authorized to view the selected data file. This step may include checking the values stored in the STB 100 (FIG. 5) and comparing these values to the required subscription level for each selected data file. Such an authentication method is described in Khoi Hoang's patent application “CONTROLLING DATA-ON-DEMAND CLIENT ACCESS” filed on July 9, 2001, application number 09 / 902,503. Other methods of authenticating access to the selected data file may include two-way communication with DOD server 200 (FIG. 5) or other remote site.
[0032]
If the user is authorized to view the selected data file (step 308), the process proceeds to step 309. In step 309, the STB starts storing the selected file. In step 310, the STB plays the selected title for viewing by the user.
[0033]
If the user is not allowed to view the selected data file (step 308), the STB displays a message at step 312 denying access. The STB may also display a message indicating how the user can access the denied service.
[0034]
FIG. 7A illustrates another interactive authentication process 350 for purchasing a selected DOD service. Process 350 begins at step 352 where STB 100 (FIG. 5) receives an EPG program from DOD broadcast server 200 (FIG. 5). The EPG program lists all files available from the DOD server. At step 353, the user selects a title from the EPG by pressing a purchase button associated with the desired title. In step 354, the STB sends a request for permission to view the desired selection to server 200 (FIG. 5). This request is transmitted to the server 200 via a telephone modem or an up line.
[0035]
In step 356, the server 200 updates the billing system by sending permission for the selected title to the requesting STB and recording the user's account. The grant is sent to the transmission medium 52 (FIG. 5) via either the modem or downstream. In step 358, the STB receives the permission and starts storing the requested title. In step 360, the STB plays the selected title for viewing by the user.
[0036]
FIG. 8 is a diagram illustrating an example of a broadcast of two separate small data files 400, such as a karaoke file. In this example, two titles are broadcast repeatedly over two separate bandwidths of the same channel. The first title 402 (Title 1) has a playback time of 2 minutes and requires 1 minute to download. The second title 404 (title 2) has a playback time of 4 minutes, and requires 2 minutes to download. Each title is repeatedly broadcast simultaneously over its assigned bandwidth.
[0037]
When the desired title (eg, title 1 and title 2) is selected (step 303 in FIG. 7), STB 100 starts downloading both title 1 and title 2 and one minute later starts playing title 1 I do. When the STB 100 starts reproducing the title 1, the STB 100 continues to download the title 2, and it takes another one minute to download the title 2. When the reproduction of the title 1 ends, the STB 100 starts the reproduction of the title 2.
[0038]
The STB 100 always assembles the data blocks using the end of one transmission for a title and the beginning of the next repeated transmission for the same title, so that each selection is always minimized. Can be downloaded. Such a process is described in Khoi Hoang's patent application “METHOD AND APPARATUS FOR TRANSMITTING NON-VOD SERVICES” filed October 25, 2000, attorney docket number 60595-301801, which is incorporated by reference. Incorporated herein. Because each file is assigned a separate transmission bandwidth, the STB can also download multiple files simultaneously.
[0039]
In a preferred embodiment, the STB 100 can download the file at a bit rate greater than the bit rate at which the file is played. In the present embodiment, the transmitted data file consists of a sequence of data blocks containing data related to the selected title. As soon as the STB receives the first data block of the sequence corresponding to the selected title, the STB can start playing the selected title. To achieve a smooth display of the title, the STB must be able to download the data block of the selected title faster than the title is played to the user. In one embodiment, the STB calculates an expected download time to determine a time at which playback of the data file can begin. This calculation is based on the encoding bit rate, transmission bit rate, and buffer block size. Since the download may be started from a data block other than the first data block of the file, the waiting time is longer than the standard download time. The time at which the STB may start playing the selected file can be calculated as follows:
[0040]
Ts ≧ Tp * (Td / Tp− (NB−1) / NB) Equation 1
[0041]
here,
Ts: data file playback start time
Tp: Time required to play data file
EBR: Encoding bit rate
TBR: Transmission bit rate
Td: time required to download the entire file (Td = file size / transmission bit rate)
NB: Number of data blocks in the file (NB = data file size / buffer block size)
[0042]
For example, when the buffer block size is 1.5 MB, a 45 MB file (NB = 30) encoded at 2 Mb / s and having a transmission rate of 1 Mb / s has a waiting time (Ts) of about 186 seconds. ). Ts = 3 × (2 / 1- (30-1) / 30) = 186 seconds. Further, when the buffer block size is 1.5 MB, a 6 MB file (NB = 4) encoded at 2 Mb / s and having a transmission rate of 1 Mb / s has a waiting time (Ts) of about 75 seconds. Having. Ts = 1 minute × (2 / 1- (4-1) / 4) = 75 seconds.
[0043]
FIG. 9 illustrates another method of transmitting a plurality of small data files over a shared bandwidth of a single transmission channel. FIG. 9 shows that a sequence of data blocks is being transmitted in a first transmission bandwidth 502 and a second transmission bandwidth 504 of an example transmission channel. The first bandwidth first transmits a first sequence of data blocks 506 corresponding to a first karaoke song, and then transmits a second sequence of data blocks 508 corresponding to a second karaoke song. Finally, the data block of the third song 510 is transmitted. The bandwidth 502 repeats the transmission of this sequence for three karaoke songs indefinitely. The second transmission bandwidth 504 transmits a fourth karaoke song 512, a fifth karaoke song 514, a sixth karaoke song 516, and a seventh karaoke song 518. The bandwidth 504 also repeats this sequence indefinitely. According to this aspect of the invention, much smaller data files are available on the same number of assigned channels, but require longer latencies.
[0044]
FIG. 10 illustrates a process 600 for receiving a digital text on demand (TOD) service, according to one embodiment of the invention. Process 600 begins at step 602 where STB 100 (FIG. 5) receives an EPG program from DOD broadcast server 200 (FIG. 5). The EPG program lists all files (books, magazines, periodicals, etc.) available from the DOD server. File types may include movies, digital text files, music, and the like. At step 604, the user selects a desired digital text file from the EPG by pressing a remote control button associated with the desired service. Note that the remote control may include an integrated mouse or rollerball. In step 606, the STB determines whether the user is authorized to view the selected digital text file. This step may include checking the values stored in the STB 100 (FIG. 5) and comparing these values to the required subscription level for each selected digital text file. Such an authentication method is described in Khoi Hoang's patent application "CONTROLLING DATA-ON-DEMAND CLIENT ACCESS" filed on July 9, 2001, application number 09 / 902,503. Other methods of authenticating access to the selected digital text file may include two-way communication with DOD server 200 (FIG. 5) or other remote site.
[0045]
If the user is authorized to view the selected file (step 606), the process proceeds to step 610. In step 610, the STB starts storing the selected file. In step 610, the STB starts storing the requested text. In step 612, the STB displays text to the user.
[0046]
In one embodiment, as many as 4000 programs (services / multiple channels) can be transmitted on one physical channel at 250 pages / channel (100,000 pages total). However, as the number of programs transmitted on one physical channel increases, the response time for accessing a desired service also increases accordingly. Each program can include multiple pages. Programs with more pages require longer access times. The program may include a page index that describes the contents of each text page.
[0047]
Text / graphic display is also possible, but requires a large amount of data and the response time increases accordingly. Available formats include, for example, JPEG and bitmap. Pages may include text and graphic images. The page may further include a hypertext language (such as HTML).
[0048]
Text files may include publications such as newspapers, magazines, books, and government publications. Other information available in text may include weather, transportation schedules, hotel information, stock information, shopping, breaking news, and third party billing services.
[0049]
FIG. 11 illustrates a process 700 for performing a transaction on a display page in accordance with the present invention. At step 702, the STB receives a text page that includes one or more interactive transaction features. In step 704, the STB displays the page to the user. The transaction function is visually indicated on the displayed page. These functions may be shown in bold or color differences. Possible transaction functions may include icons for making payments to third parties, icons for purchasing selected goods and services, icons for voting in political elections, and the like. For example, the mail order channel page may have an icon for purchasing the selected product. The stock channel page may have buy order icons indicating various stocks, quantities or prices.
[0050]
At step 706, the user activates the selected transaction function. In step 708, the STB sends a message corresponding to the content of the selected function to a location corresponding to the organization corresponding to the selected function. For example, if a user double-clicks on an icon that buys 100 shares of IBM for $ 100, the STB will, via a telephone modem, local area network, or other connection, open the stock broker associated with the icon. Send a message to the website requesting the purchase. For example, if the user selects the gas bill payment icon, the STB sends a message permitting the transfer to an appropriate public facility.
[0051]
In step 710, the receiving site performs a function corresponding to the particular message sent. For example, a mail-order company ships goods according to an order message.
[0052]
The above examples illustrate some typical embodiments of the present invention, and those skilled in the art can easily derive other embodiments, modifications, and modifications from these. Accordingly, the invention is not limited to the specific embodiments described above, but is defined by the appended claims.
[Brief description of the drawings]
[0053]
FIG. 1 is a simplified functional block diagram illustrating a prior art DOD system.
FIG. 2 is a simplified functional block diagram showing a prior art STB.
FIG. 3 is a block diagram illustrating a conventional method for DOD transmission over a network.
FIG. 4 is a simplified block diagram illustrating a DOD broadcast server according to one embodiment of the present invention.
FIG. 5 is an operational block diagram illustrating a DOD server system according to one embodiment of the present invention.
FIG. 6 is a block diagram illustrating a sophisticated set-top box according to one embodiment of the present invention.
FIG. 7 is a flowchart illustrating a method for downloading a data file according to one embodiment of the present invention.
FIG. 7A illustrates another two-way authentication process for purchasing a selected DOD service, according to one embodiment of the present invention.
FIG. 8 is a simplified diagram illustrating data block transmission in accordance with one embodiment of the present invention.
FIG. 9 is a simplified diagram illustrating data block transmission in accordance with another embodiment of the present invention.
FIG. 10 is a flowchart illustrating an operation of downloading a text / graphic file according to an embodiment of the present invention.
FIG. 11 is a flowchart illustrating a text / graphics file transaction, according to one embodiment of the invention.
[Explanation of symbols]
[0054]
10 Data-on-demand system
12 ... TV
14… Set Top Box
16 ... Wide area network
18 ... DOD server
20 ... Disk array
22 ... Transport stream demultiplexer
24 ... Video decoder
26 ... Audio decoder
28 clock control unit
29 ... Demodulator
52 Data network
100 ... receiving STB
102 ... QAM demodulator
104 ... CPU
108: Local memory
110 ... buffer memory
112 ... Decoder
114 ... Graphics overlay module
118 ... User interface
120 ... communication line
122: Data bus
124 output device
200 ... DOD server
202: Central control server
204: Central storage
206: Data bus
211 ... Channel server
212 ... Up converter
214 ... Combiner / Amplifier
400 ... data file
402 ... First title
404 ... second title
502... First transmission bandwidth
504: second transmission bandwidth
506: Data block
508: Data block
510 ... data block
512: Data block
514 ... data block
516: Data block
518 ... data block

Claims (41)

A method of transmitting a large number of small data files to a large number of consumers,
A method comprising transmitting multiple data files to multiple users simultaneously, wherein at least one of the data files is transmitted at a rate greater than a playback rate of the data files. The method of claim 1, comprising transmitting an electronic program guide (EPG) to the plurality of users, wherein the user selects the selected data file using the electronic program guide. May be the way. The method of claim 1, wherein each data file is transmitted repeatedly. 4. The method of claim 3, wherein each data file has an allocated bandwidth, and wherein the data files are transmitted repeatedly with a corresponding allocated bandwidth. 3. The method of claim 2, wherein an icon corresponding to each data file is displayed by the EPG, and a user can select the data file by selecting the displayed icon. The method of claim 1, wherein at least one of the plurality of data files is a karaoke music file that includes audio and video data. The method of claim 1, wherein at least one of the plurality of data files is a text file containing text information. The method of claim 7, wherein the text file includes a plurality of pages, and at least one page includes text information. The method of claim 8, wherein at least one of the pages includes a graphic image. The method of claim 9, wherein the graphic image is formatted as a JPEG image. 9. The method according to claim 8, wherein at least one of the plurality of pages is an index including information indicating the content of at least one other page. The method according to claim 7, wherein a service corresponding to a transaction function included in the text file may be activated by the first user. 13. The method according to claim 12, wherein a set top box (STB) transmits an electronic message in response to the activation of the transaction function. 14. The method of claim 13, wherein the electronic message includes an order to purchase goods from a third party. 14. The method of claim 13, wherein the electronic message includes an order to purchase a service from a third party. 14. The method of claim 13, wherein the electronic message includes an order instructing remittance to an account for payment. A method of downloading a regularly broadcast data file using a high-performance STB,
Receiving user input indicating at least one selected data file;
Initiating an authorized download for at least a first portion of the selected data file that is broadcast during the first time interval;
Displaying at least a portion of the first portion of the selected data file;
Obtaining a second portion of the data file broadcast during the second time interval, wherein at least a portion of the first portion is displayed during the second time interval. , The acquisition process,
Displaying at least a portion of the second portion of the selected data file;
A method comprising: The method of claim 17, further comprising:
Obtaining a further portion of the data file that is broadcast during a further time interval;
Relocating all said parts to reconstruct a complete data file;
A method comprising: The method of claim 17, further comprising:
Determining a waiting time required to play the data file, and enabling a data block corresponding to the data file to be received by a time scheduled for playing. An apparatus for obtaining a data file that is repeatedly broadcast over at least a first time interval and a second time interval,
Means for receiving a file request from a user selecting at least one of the broadcasted data files;
Means for initiating an authorized file acquisition process for acquiring at least a first portion of the data file broadcast during the first time interval;
Means for displaying at least a portion of the first portion of the data file during at least a portion of the second time interval;
Means for obtaining a second portion of the data file broadcast during the second time interval;
Means for displaying at least a portion of the second portion of the data file;
An apparatus comprising: 21. The apparatus of claim 20, further comprising: means for requesting permission to obtain the requested file. 21. The device of claim 20, further comprising:
Means for obtaining a third portion of the data file broadcast during a third time interval;
Means for rearranging said first, second and third parts to reconstruct a complete data file;
An apparatus comprising: 21. The apparatus of claim 20, wherein the EPG is received by a user's STB and presented to the user. 21. The apparatus of claim 20, wherein the user's STB automatically determines a download time and a play time from data transmitted with the EPG corresponding to the user's file selection and a wait time. An apparatus, wherein at least a portion of the file is automatically displayed later, and the duration of the waiting time depends on the download time and the playback time. 22. The apparatus according to claim 21, wherein the STB of the user automatically calculates a duration of a waiting time according to the reproduction time and the download time. 23. The apparatus according to claim 22, wherein the waiting time is further determined according to a number of data blocks constituting the file. An apparatus for obtaining a data file that is repeatedly broadcast over at least a first time interval and a second time interval,
An input device for receiving a file request from a user selecting at least one of the broadcasted data files;
A processor for initiating an authorized file acquisition process for acquiring at least a first portion of the data file broadcast during the first time interval;
An output device for displaying at least a portion of the first portion of the data file during at least a portion of the second time interval;
With
The apparatus wherein the processor is further operable to obtain a second portion of the data file that is broadcast during the second time interval. 28. The apparatus of claim 27, further comprising a communication port for requesting permission to obtain the requested file. 28. The apparatus of claim 27, wherein the processor is further configured to obtain a third portion of the data file that is broadcast during a third time interval; and the first, second, and third And a function of rearranging parts of the data to reconstruct a complete data file. 28. The apparatus of claim 27, wherein the EPG is received by a user's STB and presented to the user. 28. The apparatus of claim 27, wherein the user's STB automatically determines download and playback times from data transmitted with the EPG corresponding to the user's file selection, and after a wait time. Apparatus for automatically displaying at least a portion of the file, wherein the duration of the waiting time is determined according to the download time and the playback time. 29. The apparatus according to claim 28, wherein the STB of the user automatically calculates a duration of a waiting time according to the reproduction time and the download time. 30. The apparatus according to claim 29, wherein the waiting time is further determined according to a number of data blocks making up the file. A data-on-demand (DOD) broadcast system for transmitting a number of small data files,
A DOD broadcast server for broadcasting a plurality of data files,
A transmission medium communicatively connected to the DOD broadcast server;
A plurality of receivers communicatively connected to the DOD broadcast server via the transmission medium;
With
The DOD broadcast server repeatedly transmits a plurality of data files to the plurality of receivers via the transmission medium,
The receiver has a function that allows a user to select at least one data file;
The receiver has a function of performing a permission check on the selected data file,
The receiver further has a function of receiving the selected data file,
The receiver further has a function of displaying a part of the selected data file to the user,
system. A set top box device for accessing a plurality of small DOD data files broadcast over a wide area network,
A user input device for selecting a desired data file;
A first communication link for requesting permission to access the selected data file;
A second communication link for receiving permission to access the selected data file;
A processor for tuning to a bandwidth corresponding to the selected data file;
A third communication link for receiving the selected data file;
An apparatus comprising: 36. The device according to claim 35, further comprising a display device for displaying at least a portion of the selected data file. 36. The apparatus of claim 35, wherein the processor further automatically starts displaying the selected data file upon receiving a minimum portion of the selected data file. A device having a function. 37. The apparatus according to claim 36, wherein the input device further has a function of receiving a user input for activating a transaction function, and the visual data associated with the transaction function comprises: Appears through the device. A DOD broadcast server device for transmitting a large number of small DOD data files to a large number of recipients via a wide area network,
A storage server for storing data files,
A channel server for obtaining the selected data file from the storage server;
A transmitter for repeatedly transmitting the first data file over the allocated bandwidth so that the receiver can access the first data file within a predetermined time period;
An apparatus comprising: 40. The apparatus of claim 39, wherein the time period is shorter than a time period required to download the first data file. The apparatus of claim 39, further comprising:
A service permission processor having a function of receiving a request for permission from the client and a function of providing the client with a permission code for viewing the selected data file, wherein the service permission processor further comprises: A function of transmitting information indicating the data file to the billing device,
The billing device has a function of updating a billing record to a client according to the information,
apparatus.

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