WO2017122301A1

WO2017122301A1 - Content data reproducing device, content data reproducing method, and content data reproducing program

Info

Publication number: WO2017122301A1
Application number: PCT/JP2016/050885
Authority: WO
Inventors: 純也氏家; 幹郎佐々木; 伸輝岡田; 哲史藤▲崎▼
Original assignee: 三菱電機株式会社
Priority date: 2016-01-13
Filing date: 2016-01-13
Publication date: 2017-07-20
Also published as: JPWO2017122301A1; JP6076550B1

Abstract

This content data reproducing device reproduces non-compressed content data which is obtained by decoding compressed content data. When the content data reproducing device is powered on, a last-content data reproducing unit starts to reproduce last-content data, which is non-compressed content data last reproduced immediately before power-off of the content data reproducing device, before commencement of decoding of compressed content data.

Description

Content data playback device, content data playback method, and content data playback program

The present invention relates to a technology for reproducing content data.
The content data is audio data and video data. Hereinafter, a technique for reproducing audio data as an example of content data will be described.

The in-vehicle audio device has a function of reproducing audio data recorded on a medium such as a USB (Universal Serial Bus) memory in addition to a function of reproducing data recorded on a CD (Compact Disc). In addition, there is a function of encoding data recorded on a CD or the like and storing it in a nonvolatile storage device such as an HDD (Hard Disk Drive) in the device and reproducing the encoded data.

Furthermore, some in-vehicle audio devices have a function of reproducing audio data (this is called “last audio”) that is being reproduced immediately before the power is turned off, when the power is next turned on.
In Patent Document 1, the last cause of registration in the database not being in time by devising a database construction procedure for managing the folder and file structure in the external media for audio data recorded on the external media. A method for avoiding audio playback failure is disclosed.

Further, in Patent Document 2, a resume parameter used for returning a state of an application program (hereinafter simply referred to as an application) is selected in the nonvolatile storage device by selecting a parameter necessary for restarting the operation, and saved in the nonvolatile storage device. A method of stably restarting the operation of an application while suppressing the size of a resume parameter to be disclosed is disclosed.

JP 2008-293383 A WO2009 / 128232 publication

However, Patent Document 1 and Patent Document 2 do not have any special consideration regarding the time from when the audio device is turned on until the last audio playback is started. In other words, in any patent document, processing such as OS (Operating System) startup, device driver loading and initialization of related hardware, and startup of an audio application, which are performed after power-on, are indispensable. There is a problem that last audio playback cannot be started until the above process is completed.

With the increasing number of in-vehicle information devices including in-vehicle audio devices, the related hardware inside the SoC (System on Chip) mounted on the devices has also increased, and the time required for these initializations has also increased. Yes. For this reason, the time from when the power is turned on until the last audio playback is started also becomes longer.

This invention mainly aims to solve the above-mentioned problems, and mainly aims to shorten the time from the power-on of the content data playback device to the start of content data playback.

The content data reproducing apparatus according to the present invention is:
A content data playback device for playing back uncompressed content data obtained by decoding compressed content data,
A last content data storage unit that stores last content data that is uncompressed content data that was played back immediately before the content data playback device is powered off;
A last content data playback unit that starts playback of the last content data before starting to decode the compressed content data when the content data playback device is powered on.

According to the present invention, since the reproduction of the last content data is started before the decoding of the compressed content data is started, the time from the power-on of the content data reproduction device to the start of the reproduction of the content data can be shortened. .

FIG. 3 is a diagram illustrating a hardware configuration example of the audio reproduction device according to the first embodiment. FIG. 3 is a diagram illustrating a functional configuration example of the audio playback device according to the first embodiment. FIG. 6 shows an example of last audio information according to the first embodiment. FIG. 4 is a flowchart showing an operation example of the audio reproduction device according to the first embodiment. FIG. 4 is a flowchart showing an operation example of the audio reproduction device according to the first embodiment. FIG. 4 is a flowchart showing an operation example of the audio reproduction device according to the first embodiment. FIG. 4 is a flowchart showing an operation example of the audio reproduction device according to the first embodiment. FIG. 3 is a diagram illustrating a functional configuration example of the audio playback device according to the first embodiment.

Embodiment 1 FIG.
*** Explanation of configuration ***
FIG. 1 is a hardware configuration diagram illustrating an example of a hardware configuration of an audio playback device 1 according to the present embodiment.
The audio playback device 1 is an in-vehicle audio playback device, for example.
In FIG. 1, an audio playback device 1 includes an SoC 10, an SRAM (Static Random Access Memory) 20, a DRAM (Dynamic Random Access Memory) 30, an HDD 40, a CD drive 50, a USB connector 60, an Audio DAC (Digital to Analog 70), A and a speaker 90 are provided.
The audio playback device 1 is an example of a content data playback device.

The SoC 10 includes two or more CPU (Central Processing Unit) cores, peripheral devices (DMAC (DMA Controller) 103, counter 104, mixer 105, decoder 106, I2S (Inter-IC Sound) device 107, I2C (Inter-Integrated). IC (Integrated Circuit) provided with a Circuit device 108).
In FIG. 1, the SoC 10 includes two CPU cores (a CPU core 101 and a CPU core 102), and these CPU cores execute programs such as an OS, a driver, and an application read from the HDD 40. The CPU core uses data read from the SRAM 20, DRAM 30, or HDD 40 during program execution.
A program operating on the CPU core 101 and the CPU core 102 may acquire the state of the peripheral device and control the operation of the peripheral device by reading and writing data at a physical address unique to each peripheral device. Is possible.
The CPU core 101 and the CPU core 102 may be of the same type or different types.
The CPU core 101 is an example of a first processor, and the CPU core 102 is an example of a second processor.

The DMAC 103 controls DMA transfer between the SRAM 20 and the DRAM 30 outside the SoC 10 and other devices.

The counter 104 stores the number of clock interrupts since the SoC 10 is turned on (the clock is not shown). If the number of clock interrupts per second is unchanged, the elapsed time since the SoC 10 is turned on can be calculated by using the number stored in the counter 104 and the number of clock interrupts per second. Is possible.

The mixer 105 mixes two or more audio inputs and generates one audio output. It is assumed that the volume ratio of voice input during mixing can be changed by a program.

The decoder 106 decodes audio data (hereinafter referred to as “compressed audio data”) encoded by an audio compression method such as MP3 or AAC (registered trademark).

The I2S device 107 transmits audio data to the AudioDAC 70 via the I2S bus. In this embodiment, the AudioDAC 70 is a stereo PCM (Pulse).
Code Modulation) shall be handled.
Hereinafter, audio data input to the AudioDAC 70 will be referred to as uncompressed audio data. Uncompressed audio data is an example of uncompressed content data.

The I2C device 108 is a control device. In the present embodiment, the I2C device 108 is used for reading and writing the registers included in the AudioDAC 70 and the amplifier 80.

The SRAM 20 is a semiconductor memory that does not require periodic refresh processing. In the present embodiment, it is assumed that the SRAM 20 is provided with a battery, and the stored contents can be retained for several days even when the power of the audio playback device 1 is turned off.
The SRAM 20 stores last audio information. The last audio information includes last audio. The last audio is uncompressed audio data that was played back immediately before the audio playback device 1 was turned off. The last audio corresponds to an example of last content data.
As described above, the SRAM 20 stores the last content data and corresponds to an example of the last content data storage unit.
Note that “immediately before the power is turned off” is when the user instructs to turn off the power by a switch operation or the like.

The DRAM 30 is a semiconductor memory that requires periodic refresh processing, and is used as a main storage device of the audio playback device 1.

The HDD 40 stores an OS, a driver, an application program, etc., and encoded audio data.
The encoded audio data stored in the HDD 40 is referred to as compressed audio data. The compressed audio data corresponds to an example of compressed content data.

The CD drive 50 is a device that reads data recorded on a music CD and a data CD. The audio reproducing apparatus 1 may encode the data in the music CD inserted into the CD drive 50 and record it on the HDD 40, reproduce the compressed audio data in the data CD, or record it on the HDD 40. Is possible.

The USB connector 60 is an interface used when a USB compatible device is connected to the audio playback device 1. The audio playback device 1 can read and play back the compressed audio data stored in the USB memory connected to the USB connector 60. In addition, the audio reproduction device 1 can record the compressed audio data stored in the USB memory in the HDD 40.

The AudioDAC 70 is a device that converts the audio data input from the I2S device 107 into an analog signal and inputs the analog signal to the amplifier 80.

The amplifier 80 is a device that amplifies the analog signal input from the AudioDAC 70 and inputs it to the speaker 90.

The speaker 90 is a device that reproduces an analog signal input from the amplifier 80.

FIG. 2 is a functional configuration diagram illustrating an example of a functional configuration of the audio playback device 1 according to the first embodiment.
2, the audio playback device 1 includes a control unit 201, a control unit 202, a playback information acquisition unit 203, a time management unit 204, a communication unit 205, an uncompressed data reading unit 206, a compressed data reading unit 207, a decoding unit 208, An audio data storage unit 209, a timing adjustment unit 210, an audio switching unit 211, and an audio output unit 212 are provided.

The control unit 201 controls reproduction of uncompressed audio data (last audio) stored in the SRAM 20 and transfer of reproduction processing authority to the control unit 202.

The control unit 202 controls the reproduction of the compressed audio data recorded in the HDD 40.

The reproduction information acquisition unit 203 acquires information necessary for the calculation of the reproduction stop position of the last audio and the decoding start position of the compressed audio data by the control unit 202. Details of the information acquired by the reproduction information acquisition unit 203 will be described later.

The time management unit 204 manages the elapsed time since the audio playback device 1 is turned on.

The communication unit 205 exchanges data between the control unit 201 and the control unit 202.

The uncompressed data reading unit 206 reads the uncompressed audio data stored in the SRAM 20 and outputs it to the audio switching unit 211.

The compressed data reading unit 207 reads the compressed audio data stored in the HDD 40 and outputs it to the decoding unit 208.

The decoding unit 208 converts the compressed audio data input from the compressed data reading unit 207 into uncompressed audio data.
The uncompressed audio data converted by the decoding unit 208 corresponds to an example of uncompressed content data.

The audio data storage unit 209 temporarily stores the uncompressed audio data input from the decoding unit 208.

The timing adjustment unit 210 associates the uncompressed sound data stored in the sound data storage unit 209 with the uncompressed sound data read by the uncompressed data reading unit 206, and based on the result of the association, the sound switching unit The operation of 211 is controlled.

The audio switching unit 211 outputs one of the uncompressed audio data input from the uncompressed data reading unit 206 and the audio data storage unit 209 or uncompressed audio data obtained by mixing them to the audio output unit 212.

The audio output unit 212 converts the uncompressed audio data input from the audio switching unit 211 into an analog signal and outputs the analog signal.

Next, the correspondence relationship between the hardware components shown in FIG. 1 and the functional components shown in FIG. 2 will be described.

The control unit 201 is a program executed by the CPU core 101. The control unit 202 is a program executed by the CPU core 102.

The reproduction information acquisition unit 203 is a program that is executed by the CPU core 102 and reads data stored in the SRAM 20.

The time management unit 204 is a program that calculates the elapsed time from when the audio playback device 1 is turned on using the count value stored in the counter 104. The time management unit 204 may be executed by either the CPU core 101 or the CPU core 102.

The communication unit 205 is a specific area of the DRAM 30. It should be noted that the area is divided for each application, and it is assumed that the control unit 201 and the control unit 202 have notified which part has what meaning and what data is stored.

The uncompressed data reading unit 206 is a program that is executed by the CPU core 101 and reads data stored in the SRAM 20.

The compressed data reading unit 207 is a program that is executed by the CPU core 102 and reads compressed audio data stored in the HDD 40.
In addition, the compressed data reading unit 207 uses the DMAC 103 for non-compressed audio data transfer to the audio switching unit 211.

The decoding unit 208 is the decoder 106.

The audio data storage unit 209 is a program that is executed by the CPU core 102 and stores uncompressed audio data in a storage area. The audio data storage unit 209 stores uncompressed audio data in a specific area of the DRAM 30 or the SRAM 20.
The audio data storage unit 209 uses the DMAC 103 for uncompressed audio data transfer to the audio switching unit 211.
Control of the DMAC 103 may be directly executed by the voice data storage unit 209 or may be requested to the control unit 201 via the communication unit 205.

The timing adjustment unit 210 is a program that operates on the CPU core 101.

The audio switching unit 211 is the mixer 105, the I2S device 107, and the I2C device 108.

The audio output unit 212 is an AudioDAC 70, an amplifier 80, and a speaker 90.

As will be described later, the control unit 201 and the non-compressed data reading unit 206 start playing the last audio before starting to decode the compressed audio data when the audio playback device 1 is turned on. Therefore, the control unit 201 and the uncompressed data reading unit 206 correspond to an example of a last content data reproducing unit as shown in FIG.
In this specification, “reproduction of last content data (last audio)” means that the uncompressed data reading unit 206 reads the last content data (last audio) from the SRAM 20 and the uncompressed data reading unit 206 is the last content. Data (last audio) is output to the audio switching unit 211.
Further, the control unit 201 and the uncompressed data reading unit 206, which are the last content data playback unit, start decoding of the compressed content data (compressed audio data), and obtain the uncompressed content obtained by decoding the compressed content data (compressed audio data). After the data (uncompressed audio data) can be reproduced, the reproduction of the last content data (last audio) is stopped.
Note that “reproduction of uncompressed content data (uncompressed audio data)” means that the audio data storage unit 209 acquires non-compressed content data (uncompressed audio data) from the decoding unit 208, and the audio data storage unit 209 does not It means that compressed content data (uncompressed audio data) is output to the audio switching unit 211. Depending on the context, it is also expressed as “reproduction of compressed content data (compressed audio data)”, which has the same meaning as “reproduction of uncompressed content data (uncompressed audio data)”.

Further, as will be described later, the control unit 202 does not generate gaps or overlaps between audio data when stopping the reproduction of the last audio and starting the reproduction of the uncompressed audio data obtained by decoding the compressed audio data. The playback stop position and the decoding start position of the compressed audio data are designated. Therefore, the control unit 202 corresponds to an example of a position specifying unit as shown in FIG.

Also, the compressed data reading unit 207 corresponds to an example of a compressed content data reading unit in order to read compressed content data (compressed audio data) from the HDD 40.

Also, the audio data storage unit 209 corresponds to an example of the last content data storage unit because the uncompressed content data (uncompressed audio data) acquired from the decoding unit 208 is stored in the SRAM 20 which is the last content data storage unit.

FIG. 3 shows an example of the configuration of the last audio information 300 stored in the SRAM 20 according to the present embodiment.
In FIG. 3, the last audio information 300 is composed of a file path, playback restart time, buffer start address, buffer end address, audio data start address, audio data end address, and uncompressed audio data storage area. May be included.

The file path is information that can uniquely identify the storage location of the compressed audio data before decoding of the uncompressed audio data that was played back immediately before the previous shutdown of the audio playback device 1.
The reproduction resumption time is information for designating from what second of the compressed audio data the reproduction starts when resuming the reproduction of the compressed audio data that can be specified by the file path. That is, the playback restart time is the last audio playback start position.
When the compressed audio data is played back from the beginning, the playback restart time is 0 second. Further, the unit of the playback resumption time may be seconds or a finer unit.
The uncompressed audio data accumulation area is an area for accumulating uncompressed audio data that has been reproduced immediately before the previous shutdown of the audio reproduction apparatus 1, that is, last audio. The uncompressed audio data storage area is a ring buffer. The last audio information 300 includes a buffer start address, a buffer end address, an audio data start address, and an audio data end address as parameters for controlling the ring buffer.
The buffer head address is the head address of the uncompressed audio data storage area. The buffer end address is the end address of the uncompressed audio data storage area. The audio data start address is the start address of the audio data in the uncompressed audio data storage area, and the position is changed every moment by the reproduction processing by the audio reproducing apparatus 1. The audio data end address is the end address of the audio data in the uncompressed audio data storage area, and the position is changed every moment by the decoding of the compressed audio data by the audio reproducing apparatus 1. That is, uncompressed audio data before being output by the audio output unit 212 is stored in the uncompressed audio data storage area.
In FIG. 3, the central part of the uncompressed audio data storage area is an unused area, the head part of the uncompressed audio data is stored on the lower side, and the continuation of the uncompressed audio data is stored on the upper side. Represents a state.

The size of the uncompressed audio data stored in the uncompressed audio data storage area can be obtained by the following equation.
・ When audio data start address> audio data end address (state in Fig. 3)
(Buffer end address-Audio data start address)
+ (Voice data end address-buffer start address)
・ When voice data start address <voice data end address (voice data end address-voice data start address)
・ When voice data start address = voice data end address 0

In addition, the uncompressed audio data stored in the uncompressed audio data storage area can be obtained by integrating the specifications of the uncompressed audio data handled by the audio playback device 1 (number of quantization bits, sampling frequency, stereo / monaural, etc.). By using the size of the data, it is possible to calculate how many seconds the accumulated audio data corresponds to. If there are two or more specifications of uncompressed audio data handled by the audio playback device 1, information that can uniquely specify each specification may be included in the last audio information 300.

*** Explanation of operation ***
Next, the operation of the audio playback device 1 will be described with reference to FIGS. 1, 2, 3, 4, 5, 6, and 7. FIG.
In the following, it is assumed that uncompressed audio data of compressed audio data recorded in the HDD 40 immediately before the previous shutdown of the audio playback device 1 is played back, and the last audio information 300 is stored in the SRAM 20. . That is, it is assumed that the uncompressed audio data reproduced immediately before the shutdown is accumulated in the uncompressed audio data storage area of the last audio information 300 in the SRAM 20 as the last audio.
In the following, it is assumed that the CPU core 101 and the CPU core 102 individually execute the OS.
The CPU core 102 initializes many devices and activates a plurality of applications. For this reason, it is assumed that an application running on the CPU core 102 takes a longer time to start than an application running on the CPU core 101.
That is, when only the OS that runs on the CPU core 102 is executed in the audio playback device 1, it is assumed that a long time is required to start playback of the last audio.

FIG. 4 is a flowchart showing an operation centered on the control unit 201 when the audio playback device 1 is activated in the present embodiment.
4, 5, 6, and 7 correspond to examples of a content data playback method and a content data playback program.

(ST1001): The control unit 201 activates the OS, and loads only a driver related to audio output as part of the activation process. In addition, the control unit 201 initializes hardware corresponding to the loaded driver so that the hardware can be used.
The control unit 201 sets the audio switching unit 211 (mixer 105) to use only the audio data from the uncompressed data reading unit 206. In addition, the control unit 201 sets the audio switching unit 211 (mixer 105) not to supply audio data to the audio output unit 212 at this time.

(ST1002): The control unit 201 initializes the communication unit 205.

(ST1003): The control unit 201 inquires of the time management unit 204 about the elapsed time (hereinafter simply referred to as elapsed time) after the audio playback device 1 is turned on. In addition, the control unit 201 notifies the control unit 202 of the obtained elapsed time via the communication unit 205 and also stores the elapsed time in the control unit 201.
The control unit 201 inquires of the time management unit 204 about the elapsed time when the uncompressed data reading unit 206 can read the last audio from the SRAM 20, that is, when the last audio can be reproduced. Thus, the elapsed time obtained in ST1003 is the time from when the audio playback device 1 is turned on until the last audio can be played back.
The “notification” means writing notification contents in a specific area of the DRAM 30, and the control section 202 can use the notification contents by referring to the area at an arbitrary timing.

(ST1004): The control unit 201 starts a process of waiting for a notification from the control unit 202 via the communication unit 205. Specifically, the control unit 201 generates a dedicated task or thread, confirms the contents of a specific area of the DRAM 30 at a certain period, or waits for an interrupt.
That is, control section 201 can perform ST1004 and the processing after ST1005 in parallel.
The operation when a notification arrives from the control unit 202 will be described with reference to FIG.

(ST1005): The control unit 202 instructs the uncompressed data reading unit 206 to start processing. In response to this instruction, the uncompressed data reading unit 206 reads the uncompressed audio data stored in the SRAM 20. In addition, the uncompressed data reading unit 206 passes the uncompressed audio data to the audio switching unit 211 and then instructs the audio switching unit 211 to supply audio data to the audio output unit 212. Thereby, the reproduction of the last audio is started.
The audio data supply instruction to the audio output unit 212 to the audio switching unit 211 is performed only when ST1005 is executed for the first time.
The uncompressed data reading unit 206 reads the uncompressed audio data at the audio data start address of the last audio information 300, updates the audio data start address by the read size, and sets the next read start position. Since the uncompressed audio data storage area of the last audio information 300 is used as a ring buffer, the audio data head address is controlled not to be larger than the buffer end address.

(ST1006): The uncompressed data reading unit 206 confirms whether or not all the uncompressed audio data of the last audio information 300 has been read. When the audio data head address and the audio data end address of the last audio information 300 match, the uncompressed data reading unit 206 determines that “all have been read” and ends the reading process. In other cases, the uncompressed data reading unit 206 executes ST1005 again. However, the audio data supply instruction to the audio output unit 212 to the audio switching unit 211 is performed only at the first execution of ST1005. Note that the repetition processing of ST1005 and ST1006 is performed at a constant cycle.

FIG. 5 is a flowchart showing an operation centered on the control unit 202 when the audio reproducing apparatus 1 is activated in this embodiment.

(ST2001): The control unit 202 activates the OS, and loads all necessary drivers for the audio playback device 1 as part of the activation process. In addition, the control unit 202 initializes hardware corresponding to the loaded driver, and makes the hardware usable. However, the control unit 202 does not initialize the hardware that the control unit 201 has initialized.

(ST2002): The control unit 202 receives the notification content (ST1003) from the control unit 201 using the communication unit 205, and stores the received notification content in the control unit 202.
Hereinafter, the notification content (that is, the elapsed time) received in ST2002 is Time [A]. Time [A] is the time from when the audio playback device 1 is turned on until the last audio can be played back, as described above.

(ST2003): The control unit 202 uses the playback information acquisition unit 203 to acquire the file path and playback restart time of the last audio information 300, and stores the acquired file path and playback restart time inside the control unit 202.

(ST2004): The control unit 202 queries the time management unit 204 for the elapsed time, acquires the elapsed time from the time management unit 204, and stores the acquired elapsed time in the control unit 202.
Hereinafter, the elapsed time acquired in ST2004 is Time [B].
The control unit 202 inquires the time management unit 204 of the elapsed time when the compressed data reading unit 207 can read the compressed audio data from the HDD 40 and output the compressed audio data to the decoding unit 208. Therefore, the elapsed time obtained in ST2004 is the time from when the audio playback device 1 is turned on until the compressed audio data can be decoded.

(ST2005): Control section 202 calculates the difference between Time [B] and Time [A], and adds the difference to the playback restart time stored in ST2003. Furthermore, the fixed value which the control part 202 has is also added. Let the final calculation result be SeekTime.
The difference between Time [B] and Time [A] is the time from when the last audio can be reproduced until the compressed audio data can be decoded.
The fixed value is a communication delay time between the CPU core 101 and the CPU core 102.

(ST2006): The control unit 202 passes the file path stored in ST2003 and the SeekTime to the compressed data reading unit 207.
The compressed data reading unit 207 opens the file recorded in the HDD 40 using the received file path, and further reads a certain amount of the file from the portion corresponding to the received SeekTime. That is, the compressed data reading unit 207 reads the compressed audio data after the portion corresponding to SeekTime.
The compressed data reading unit 207 passes the read compressed audio data to the decoding unit 208.
The decoding unit 208 decodes the compressed audio data and outputs the obtained uncompressed audio data to the audio data storage unit 209. The audio data storage unit 209 writes uncompressed audio data in the DRAM 30, for example.
Thus, SeekTime is a parameter that specifies the decoding start position of the compressed audio data. That is, the control unit 202 designates the decoding start position of the compressed audio data by calculating SeekTime.

(ST2007): Using control unit 202, control unit 202 has a value obtained by subtracting the time corresponding to the playback restart time from SeekTime (ie, the difference between Time [B] and Time [A], and control unit 202 has The total of the fixed values) is notified to the control unit 201 as the scheduled control switching time.

(ST2008): The control unit 202 starts a process of waiting for a notification from the control unit 201 via the communication unit 205. The operation when the notification from the control unit 201 arrives will be described with reference to FIG.

FIG. 6 is a flowchart showing an operation after receiving a notification (ST2007) from the control unit 202 among the operations centering on the control unit 201 of the audio reproduction device 1 in this embodiment.

(ST3001): The control unit 201 receives a notification of the scheduled control switching time from the control unit 202 via the communication unit 205, and passes the notified scheduled control switching time to the timing adjustment unit 210 as a reference time.

(ST3002): The timing adjustment unit 210 receives the reference time from the control unit 201, stores the reference time in the timing adjustment unit 210, and inquires the elapsed time from the time management unit 204.

(ST3003): The timing adjustment unit 210 compares the reference time stored in ST3002 with the elapsed time acquired in ST3002, and confirms whether or not the reference time has elapsed since the audio playback device 1 was activated. If it has elapsed (Yes), the process proceeds to ST3005. If not (No), the process proceeds to ST3004.

(ST3004): The timing adjustment unit 210 waits for a certain period of time and then executes the processing of ST3002. That is, the operations from ST3002 to ST3004 are performed periodically.

(ST3005): The timing adjustment unit 210 sets the audio switching unit 211 to use only the audio data from the audio data storage unit 209. That is, the timing adjustment unit 210 controls the audio switching unit 211 so that uncompressed audio data obtained by decoding and stored in the DRAM 40 is output to the audio output unit 212.
Further, the timing adjustment unit 210 reports to the control unit 201 that the switching of the audio output has been completed.

(ST3006): The control unit 201 stops the operation (ST1005 and ST1006) of the uncompressed data reading unit 206.

(ST3007): The control unit 201 uses the communication unit 205 to notify the control unit 202 that the audio output switching has been completed.

ST3005 and ST3006 are performed simultaneously. That is, simultaneously with the stop of the output of the last audio to the audio output unit 212, the output of the uncompressed audio data stored in the DRAM 40 obtained by decoding to the audio output unit 212 is started.
The reproduction start position of uncompressed audio data is the data position immediately after the last audio reproduction stop position.
That is, the sound is output smoothly from the sound output unit 212 without the sound being interrupted or the two sounds being overlapped.

As shown in ST3006, the control unit 201 stops the operation of the uncompressed data reading unit 206 when the time (reference time) notified from the control unit 202 elapses. That is, the control unit 201 stops the reproduction of the last audio when the scheduled control switching time (reference time) notified from the control unit 202 elapses. In other words, the scheduled control switching time (reference time) notified from the control unit 202 designates the last audio playback stop position. That is, the control unit 202 designates the last audio playback stop position by calculating the scheduled control switching time.

FIG. 7 is a flowchart showing the operation after receiving the notification (ST3007) from the control unit 201 among the operations centering on the control unit 202 of the audio playback device 1 in the first embodiment.

(ST4001): When receiving the notification from the control unit 201 via the communication unit 205, the control unit 202 instructs the audio data storage unit 209 to change the storage destination of the uncompressed audio data obtained by decoding. That is, the control unit 202 instructs the audio data storage unit 209 to store the uncompressed audio data obtained by decoding in the SRAM 20 that is the storage destination of the last audio instead of the DRAM 30.

(ST4002): The control unit 202 instructs the compressed data reading unit 207 to resume the file reading process. That is, control section 202 instructs compressed data reading section 207 to read compressed audio data following the compressed audio data decoded in ST2006.
As a result, the compressed audio data read by the compressed data reading unit 207 is decoded by the decoding unit 208, and the uncompressed audio data obtained by the decoding is input to the audio data storage unit 209. The audio data storage unit 209 stores the uncompressed audio data obtained by decoding in the SRAM 20 in accordance with the instruction from the control unit 202 in ST4001. As a result, the uncompressed audio data obtained by decoding is sequentially written in the uncompressed audio data storage area of the last audio information 300. Then, the uncompressed audio data in the uncompressed audio data storage area of the last audio information 300 is input to the audio switching unit 211, and the audio output is continuously performed.

Note that the audio data head address and the playback restart time of the last audio information 300 are updated in conjunction with the input of uncompressed audio data to the audio switching unit 211. Also, the audio data end address of the last audio information 300 is updated in conjunction with the writing of the uncompressed audio data of the decoding result. These two operations are performed in parallel, and when there is no free space in the uncompressed audio data storage area of the last audio information 300, a cooperative operation is performed in which decoding is temporarily stopped until there is space. .
As for the file path of the last audio information 300, when the compressed data reading unit 207 opens the next reproduction target file and the first decoding is completed, that is, the decoding result is written in the uncompressed audio data storage area of the last audio information 300. It will be updated when

*** Explanation of the effect of the embodiment ***
As described above, in the audio playback device 1 according to the present embodiment, immediately after the audio playback device 1 is started, the control unit 201 is in an area where it is not necessary to wait for the mounting of the HDD 40 and uncompressed audio data that does not need to be decoded. Play.
Further, in the audio playback device 1 according to the present embodiment, the control unit 202 can perform playback start time (elapsed time) by the control unit 201, playback restart time of the last audio information 300, and decoding by the decoding unit 208. The decoding start position of the compressed audio data stored in the HDD 40 and the reproduction stop position of the last audio are determined using the time (elapsed time) that has become and the fixed value of the control unit 202.
The control unit 202 causes the decoding unit 208 to decode the compressed audio data from the decoding start position.
The control unit 201 causes the uncompressed data reading unit 206 to stop the last audio playback at the last audio playback stop position.
Further, the control unit 201 controls the switching timing using the timing adjustment unit 210 to switch from the output of the last audio to the output of the uncompressed audio data obtained by decoding.
With the above procedure, it is possible to start the reproduction of the last audio earlier than the reproduction using the compressed audio data.
Further, it is possible to switch from the output of the last audio to the output of the uncompressed audio data obtained by the decoding without interrupting the sound or overlapping the two sounds.

In the present embodiment, since the fixed value of the control unit 202 is used as the reference time used by the timing adjustment unit 210, an appropriate switching timing is missed when the operation of the timing adjustment unit 210 is started. The effect that a problem can be avoided is also obtained.

*** Additional notes ***
In the above description, the fixed values of the control unit 202 are used to calculate the playback stop position and the decoding start position. This fixed value is the communication delay time between the CPU core 101 and the CPU core 102 as described above. The fixed value may include the time required for processing execution by each control unit.
If this fixed value is too large, switching from reproduction by the control unit 201 (last audio reproduction) to reproduction by the control unit 202 (reproduction of uncompressed audio data obtained by decoding compressed audio data) is delayed. During playback by the control unit 201, the user of the audio playback device 1 cannot perform operations that are possible when playback by the control unit 202 is being performed, such as fast-forwarding or skipping to the next song. Therefore, it is desirable to make this fixed value as small as possible.
In order to reduce the fixed value, the fixed value may be changed based on the measured value of the communication delay between the control units using the communication unit 205.
Thereby, the reproduction | regeneration by the control part 202 is realizable early.

In the above description, the size of the last audio stored in the uncompressed audio data storage area of the last audio information 300 is not mentioned. However, when the data size of the last audio is less than the threshold, playback using the last audio is performed. It may not be possible.
Thereby, it is possible to avoid the problem that the audio output is interrupted because the reproduction using the compressed audio data by the control unit 202 is not in time.

In the above description, the size of the uncompressed audio data storage area of the last audio information 300 is not mentioned, but the audio data storage unit 209 stores the size of this area in the compressed audio data to be reproduced. You may change according to the kind of. For example, when the compressed audio data in the data CD inserted in the CD drive 50 is reproduced, the time until the file access becomes possible is often longer than when the compressed audio data in the HDD 40 is reproduced. When the storage medium of the compressed audio data to be reproduced is the data CD, the audio data storage unit 209 increases the size of the uncompressed audio data storage area of the last audio information 300.
Thereby, it is possible to avoid the problem that the audio output is interrupted because the reproduction using the compressed audio data by the control unit 202 is not in time.

In the above description, the timing adjustment unit 210 determines the switching timing (last audio playback stop timing and uncompressed audio data playback start timing) using only the reference time. Instead, the timing adjustment unit 210 may determine the switching timing with reference to the uncompressed audio data in the uncompressed data reading unit 206 and the audio data storage unit 209.
By doing in this way, the effect that it can ensure reliably that there is no interruption and duplication in the audio | voice actually output is acquired.

For example, if it is found that skipping a part of the head of the uncompressed audio data in the audio data storage unit 209 matches the uncompressed audio data in the uncompressed data reading unit 206, The data reading unit 206 may reproduce the last audio by skipping a part of the beginning of the last audio.
As a result, it is possible to solve the problem that noise is included in the output sound, and it is possible to obtain an effect that the user of the audio reproducing apparatus 1 does not have to feel uncomfortable.

Further, in the above description, the audio playback device 1 plays back the audio data after the position where the playback was interrupted immediately before the previous power-off as the last audio. For example, if the audio data is music data, if the playback is interrupted in the middle of the song immediately before the previous power-off, the song starts from the interrupted position. Instead, it may be played back as the last audio from the beginning of the audio data that has been played back immediately before the power is turned off. That is, if playback is interrupted in the middle of a song immediately before the previous power-off, playback may be started from the beginning of the song.

In the above description, an audio playback apparatus that plays back audio data as an example of content data has been described. The present invention can also be applied to a video data playback apparatus that plays back video data as content data. Also in the video data playback device, playback of uncompressed video data corresponding to the last audio is started prior to decoding of the compressed video data.

1 audio playback device, 10 SoC, 20 SRAM, 30 DRAM, 40 HDD, 50 CD drive, 60 USB connector, 70 AudioDAC, 80 amplifier, 90 speaker, 101 CPU core, 102 CPU core, 103 DMAC, 104 counter, 105 Mixer, 106 decoder, 107 I2S device, 108 I2C device, 201 control unit, 202 control unit, 203 reproduction information acquisition unit, 204 time management unit, 205 communication unit, 206 uncompressed data reading unit, 207 compressed data reading unit, 208 Decoding unit, 209 audio data storage unit, 210 timing adjustment unit, 211 audio switching unit, 212 audio output unit, 300 last audio information.

Claims

A content data playback device for playing back uncompressed content data obtained by decoding compressed content data,
A last content data storage unit that stores last content data that is uncompressed content data that was played back immediately before the content data playback device is powered off;
A content data playback device comprising: a last content data playback unit that starts playback of the last content data before starting to decode the compressed content data when the content data playback device is powered on.
The last content data playback unit
2. The content data according to claim 1, wherein after the decoding of the compressed content data is started and the non-compressed content data obtained by decoding the compressed content data can be reproduced, the reproduction of the last content data is stopped. Playback device.
The content data playback device further includes:
The reproduction stop position of the last content data and the compression in which no gap or duplication occurs between the content data when the reproduction of the last content data is stopped and the reproduction of the uncompressed content data obtained by decoding the compressed content data is started. The content data reproducing apparatus according to claim 2, further comprising a position designating unit that designates a decoding start position of the content data.
The content data playback device further includes:
A compressed content data reading unit that reads the compressed content data after the decoding start position calculated by the position specifying unit and outputs the compressed content data after the decoding start position to a decoder;
The last content data playback unit
4. The content data reproduction apparatus according to claim 3, wherein reproduction of the last content data is stopped at the reproduction stop position calculated by the position specifying unit.
The position specifying unit is
Performing a calculation based on the time from when the last content data can be reproduced by the last content data reproduction unit until the compressed content data can be decoded and the reproduction start position of the last content data, The content data reproducing apparatus according to claim 3, wherein the reproduction stop position of the last content data and the decoding start position of the compressed content data are designated.
The content data playback device includes:
A first processor and a second processor;
The first processor operates as the last content data reproduction unit;
The second processor operates as the position specifying unit and the compressed content data reading unit;
The second processor is
As the position specifying unit,
A time from when the last content data can be reproduced by the last content data reproducing unit to when the compressed content data can be decoded; a reproduction start position of the last content data; and the first processor; 5. The content according to claim 4, wherein a calculation based on a communication delay time with the second processor is performed to specify the reproduction stop position of the last content data and the decoding start position of the compressed content data. Data playback device.
The content data playback device further includes:
A last content data storage unit that stores uncompressed content data obtained by decoding the compressed content data in the last content data storage unit after the reproduction of the last content data by the last content data playback unit is stopped. 2. The content data reproducing apparatus according to 2.
The last content data playback unit
The content data reproducing apparatus according to claim 1, wherein when the size of the last content data is less than a threshold, the last content data is not reproduced.
The last content data storage unit
8. The content data reproducing apparatus according to claim 7, wherein a size of a storage area of the last content data in the last content data storage unit is determined according to a type of a storage medium storing the compressed content data.
The content data playback device further includes:
A timing adjustment unit that compares the last content data with uncompressed content data obtained by decoding the compressed content data and adjusts the reproduction stop timing of the last content data and the reproduction start timing of the uncompressed content data. Item 3. A content data reproducing apparatus according to Item 2.
The last content data playback unit
The content data reproducing apparatus according to claim 1, wherein reproduction of the last content data is started by skipping a part of the head.
The content data playback device includes:
A first processor and a second processor;
The first processor operates as the last content data reproduction unit;
The content data reproducing apparatus according to claim 1, wherein the second processor causes a decoder to decode the compressed content data and reproduces the uncompressed content data obtained by the decoding.
A content data playback device, which is a computer that plays back uncompressed content data obtained by decoding compressed content data,
Immediately before the power of the content data playback device is turned off, the last content data that has been played back is stored in a storage device,
A content data playback method for starting playback of the last content data before starting to decode the compressed content data when the content data playback device is turned on.
In a content data playback device that is a computer that plays back uncompressed content data obtained by decoding compressed content data,
Last content data storage processing for storing in a storage device last content data that is uncompressed content data that has been played back immediately before powering off the content data playback device;
A content data playback program for executing a last content data playback process for starting playback of the last content data before starting to decode the compressed content data when the content data playback device is turned on.