JP5692255B2 - Content reproduction apparatus and content processing method - Google Patents

Description

  The present invention relates to a content reproduction apparatus and a content processing method for processing sound into sound that is easy to hear according to the quality of a compressed audio signal.

  Recent television receivers include not only a tuner for receiving and playing back a television broadcast, but also a large number of input terminals such as HDMI and analog (NTSC) (see, for example, Patent Document 1). Some have a memory card slot. For example, a game device, a personal computer connected to the Internet, a home video, or the like is connected to the input terminal.

JP 2006-019947 A

  The TV broadcast video (video and audio) received by the tuner is optimized so that it can be played back satisfactorily on the TV receiver. Therefore, if the demodulated output is output as it is, the video and audio are played back with the optimized sound quality. The However, most of the moving images input from personal computers connected to various input terminals, home videos, etc. are taken by so-called amateurs or compressed at a high compression rate for distribution over the Internet or the like. Many videos taken by amateurs have little adjustment after shooting, so the volume setting is too large or too small, and if you play it as it is, the sound will be extremely loud or small There are many. In addition, many moving images compressed at a high compression rate have a high sound range removed from the sound in order to increase the compression rate. Therefore, when reproducing such a moving image on a television receiver, it is desirable to process the sound according to the quality of the moving image so as to make it easy to hear.

  The recorded video file contains attribute information such as model information of the camera used for shooting, video compression algorithm, resolution, color bit number, frame rate, audio compression algorithm, sample rate, sample bit number, bit rate, etc. Has been written. However, since a moving image input from an input terminal such as HDMI or analog is a streaming signal decoded and reproduced by an external device, such information may be lost. Therefore, the television receiver cannot determine how to process the sound of the moving image to make it easier to listen.

  In addition, AV amplifiers include devices that have a video input terminal such as HDMI or analog and supply video to a television, and a function of emitting sound from a speaker. It was the same.

  An object of the present invention is to provide a content reproduction apparatus and a content processing method capable of easily processing sound according to the type of content.

The content reproduction apparatus of the present invention inputs and reproduces audio of a predetermined bit rate, detects a bit rate of the audio, and a dynamic range of the audio to the extent corresponding to the detected bit rate. An audio processing unit that performs compression and complementation of high-frequency components. The higher the audio bit rate, the smaller the degree of compression of the dynamic range and the greater the degree of high-frequency component complementation, and the lower the audio bit rate, the greater the degree of compression of the dynamic range. Reduce the degree of ingredient complementation.

In the above invention, when the detected bit rate is a size that does not cause loss to the sound, the sound processing unit is configured not to compress the dynamic range and complement the high frequency component for the sound. Also good.

The content processing method according to the present invention includes a step of inputting and playing back audio of a predetermined bit rate, a bit rate detecting step of detecting the bit rate of the audio, and dynamic of the audio to the extent corresponding to the detected bit rate. An audio processing step for compressing the range and complementing the high frequency range component. Audio processing steps, reduce the degree of compression of the dynamic range higher bit rate of the audio, to increase the degree of complementary high frequency components, a large degree of compression of the dynamic range lower the bit rate of the audio, treble Reduce the degree of ingredient complementation.

  In the above invention, when the detected bit rate has a magnitude that does not cause loss of sound, the sound processing step may not be performed.

  According to the present invention, it is possible to estimate the frequency characteristics of the voice based on the bit rate of the voice, and to perform reliable voice processing.

The block diagram of the television receiver which is embodiment of this invention The flowchart which shows operation | movement of the video processing part and audio | voice processing part of the television receiver The figure which shows the example of the frequency characteristic of the audio | voice of the moving image input into the television receiver A flowchart showing the operation of the decoder of the television receiver The figure which shows the example of the frequency characteristic of the audio | voice of the moving image input into the television receiver Block diagram of an AV amplifier according to another embodiment of the present invention

  FIG. 1 is a block diagram of a television receiver according to an embodiment of the present invention. The television receiver 1 is a device that mainly receives a television broadcast and a moving image of a similar format and reproduces the same. In this embodiment, content including video and audio synchronized therewith is called a moving image. As tuners for receiving broadcast signals sent from broadcast stations, a terrestrial digital (terrestrial digital broadcast) tuner 21, a BS (broadcast satellite broadcast) tuner 22, and a CS (communication satellite broadcast) tuner 23 are provided. Also, an HDMI input unit 24 and an analog input unit 25 are provided as input terminals for inputting a moving image from the outside. The analog input unit 25 has a composite terminal or an S terminal + stereo terminal and the like, and incorporates an A / D converter that digitizes signals input from these terminals. A decoder (CODEC) 26 is also provided to decode the compressed moving image. For example, a network cable, a memory card slot, a USB connector, or the like is connected to the decoder 26. The decoder 26 decodes a moving image file that is streamed from the Internet via a network cable. The decoder 26 reads out a moving image file from a recording medium such as a memory card set in the memory card slot, decodes and reproduces it.

  These moving picture reproduction units (terrestrial digital tuner 21, BS tuner 22, CS tuner 23, HDMI input unit 24, analog input unit 25, and decoder 26) are connected to the input side of the selector 20. The video processing unit 11 and the audio processing unit 12 are connected to the output side of the selector 20. The selector 20 is switched by a controller 10 composed of a microcomputer. That is, among the videos input from the video playback unit, the video of the video selected by the selector 20 is input to the video processing unit 11, and the audio of the selected video is input to the audio processing unit 12.

  A display processing unit 13 is connected to the video processing unit 11, and a display 15 is connected to the display processing unit 13. In addition, a sound emission processing unit 14 is connected to the sound processing unit 12, and a speaker 16 is connected to the sound emission processing unit 14.

  The video processing unit 11 is optimized so that the TV broadcast video input from the terrestrial digital tuner 21, the BS tuner 22, and the CS tuner 23 can be displayed on the display 15 with good image quality. 13 is output. The audio processing unit 12 is optimized so that the sound of the television broadcast input from the terrestrial digital tuner 21, the BS tuner 22, and the CS tuner 23 can be emitted from the speaker 16 with good sound quality. The sound is output to the sound emission processing unit 14.

  The video processing unit 11 processes the video of the moving image input from the HDMI input unit 24, the analog input unit 25, or the decoder 26 according to the image quality of the moving image so that the user can easily view it when displayed on the display 15. To do. The video processing is, for example, processing such as adjusting resolution and video sharpness. The processed video is input to the display processing unit 13. The display processing unit 13 performs processing for expanding the video signal into a matrix to form frame data and displaying the frame data on the display 15.

  In the video processing unit 11, the video image quality is analyzed by the video analysis unit 11 </ b> A built in the video processing unit 11. The video analysis unit 11A analyzes the resolution of the video input from the HDMI input unit 24 or the analog input unit 25 via the selector 20, the degree of compression distortion, and the like. This analysis result is sent to the controller 10 in addition to being used for video processing in the video processing unit 11.

  The controller 10 estimates the sound quality based on the analysis result of the video acquired from the video analysis unit 11A of the video processing unit 11, and determines the content of the audio processing according to the estimated sound quality. The controller 10 sets the determined processing content for the voice processing unit 12. The sound processing unit 12 performs sound processing of the set contents. The audio processing includes, for example, processing for compressing or expanding a dynamic range for an audio signal having a sound quality inferior to that of television broadcasting, and component addition processing for enhancing or complementing high-frequency components. The processed voice is input to the sound emission processing unit 14. The sound emission processing unit 14 converts the sound into an analog signal, amplifies it, and emits the sound from the speaker 16.

  Further, when the decoder 26 decodes a streaming moving image sent via the network, and when decoding and reproducing a moving image file on the recording medium, the decoder 26 acquires the attribute of the moving image. The moving image attributes include a video compression algorithm, resolution, the number of color bits, a frame rate, an audio compression algorithm, a sample rate, a number of sample bits, a bit rate, and the like.

  The controller 10 acquires the attribute of the moving image from the decoder 26 when selecting the decoder 26 with the selector 20. The controller 10 sends the video attribute to the video processing unit 11 and determines the processing content of the audio processing unit 12 to compensate for the sound quality inferior to that of the television broadcast based on the audio attribute. This is set in the voice processing unit 12.

  FIG. 2 is a flowchart showing operations of the video processing unit 11 and the controller 10. FIG. 2A is a flowchart showing the video analysis operation of the video analysis unit 11 </ b> A of the video processing unit 11. An image is input (S1) and the resolution is analyzed (S2). Then, a resolution conversion coefficient for displaying the full screen on the display 15 is set (S3). Further, it is analyzed how much compression distortion is included in the video (S4). The presence or absence and degree of compression distortion can be determined by the following method. Here, a method for obtaining the degree of block noise, which is an example of compression distortion, is shown. The brightness change of an arbitrary vertical dot row and horizontal dot row of an image is obtained, and if there is a discontinuous point at regular intervals (for example, 16 dots), there is a block noise, and the larger the difference between the discontinuous points, the more the block noise level Can be determined to be large. Depending on the magnitude of the detected block noise, processing such as softening the video is set so as to make the block edge inconspicuous (S5). Similarly, another example of compression distortion and its processing includes detecting and removing the degree of mosquito noise.

  Then, the actual frame rate is analyzed (S6). In the case of a moving image input from the HDMI input unit 24, the frame rate is adjusted to, for example, 60 fps or 120 fps. However, there is a possibility that an original moving image having a lower frame rate is converted to the frame rate when it is converted into an HDMI signal. Therefore, it is considered that the frame rate was increased when the motion of the plurality of intra-frame images was checked and if the motion was stepwise, the HDMI signal was converted. That is, even if the image is 60 fps, if the image actually moves only every three frames, it can be estimated that the image was originally 20 fps. In this way, the actual frame rate is estimated. Since the video has already been converted for HDMI, this analysis result is not used for video processing.

  Then, the analyzed resolution, compression distortion strength, and actual frame rate are transmitted to the controller 10 (S7). After that, the video processing unit 11 executes video processing according to the setting contents of S3 and S5.

  FIG. 2B is a flowchart showing an audio processing setting operation by the controller. When the resolution, compression distortion strength, and actual frame rate are acquired from the video processing unit 11 (S11), the degree of conversion of the dynamic range is determined based on the resolution (S12), and the degree of expansion of the audio frequency component is determined. (S13).

  There are several methods for dynamic range conversion. In other words, “The poorer video with a lower bit rate is compressed because the dynamic range is compressed, so this is expanded,” “Professional technology is used by using a consumer video camera that is not a dedicated broadcast device. Since there are no so-called amateur videos, the audio signal level varies, so the dynamic range is compressed to make it easier to remove small sounds, or excessive sounds are limited with a limiter and played on a TV. For example, a method of “optimizing for possible volume”. In S12, dynamic range conversion is performed by combining any one or each of these methods. In addition, the frequency component expansion is estimated from the resolution, the actual frame rate, and the compression distortion strength in S13 because the high frequency range and the low frequency range are often cut in order to increase the compression rate as the moving image has a lower bit rate. Reinforce the high and low frequencies according to the bit rate.

  The audio processing unit 12 is set to execute the determined processing content (S14), and the audio processing setting operation is terminated. Through the above operation, the result of the video analysis performed by the video processing unit 11 to determine the processing content of the video is acquired, and the content of the audio processing of the audio processing unit 12 is set.

  In video analysis, based on the camera work, that is, the skill of panning and zooming, it is estimated whether the image is taken by a professional or an amateur and whether or not dynamic range compression is performed based on the estimation result You may decide.

  The skill of panning / zooming can be estimated by the following method. For example, “too much panning / zooming”, “panning / zooming is too fast or uneven”, “panning is coming back and forth, and it ’s blurry Changes in video that would not occur if shooting by a professional photographer, such as “waving”, are detected, and if these are detected, it is determined that shooting is by a home video camera. If the connected device is a video camera, the audio processing content may be determined based on the input resolution information. However, in the case of a video camera, the dynamic range of the audio is often too wide. DRC) is set to a stronger value.

  Here, an example of a method for determining the contents of the frequency component expansion process (S13) and the dynamic range conversion process (S12) according to the resolution of the video acquired from the video analysis unit 11A will be described. In the case of compressed moving image data or analog moving images, it is considered that the video resolution and the sound quality (bit rate) of audio are substantially correlated. Therefore, the contents of the audio processing are determined as follows according to the resolution of the video.

When the video resolution is 240p (the number of vertical scanning lines is 240), as shown in FIG. 3A, the audio frequency characteristic extends only to around 6 kHz, and the high-frequency band that can be emphasized is hardly detected. For this reason, expansion is desirable only on the low frequency side. The original components (quantization noise, etc.) are suppressed and added to the eyes so that they do not stand out. Since the band is narrow and the sound pressure balance is broken, the dynamic range compression processing (DRC) is strongly applied. That is,
High frequency component added None Low frequency component added -6dB
DRC strong.

When the video resolution is 360p, as shown in FIG. 3B, the audio frequency characteristic extends to around 10 kHz in the high sound range. For this reason, it is desirable to add a component of several kHz or more as a high-frequency extension component. The original components (quantization noise, etc.) are suppressed and added to the eyes so that they do not stand out. Since the band is narrow and the sound pressure balance is broken, the DRC is put stronger. That is,
High frequency component added -6dB
Low side component added -6dB
DRC strong.

When the video resolution is 480p, as shown in FIG. 3C, the audio frequency characteristic extends to around 16 kHz in the high sound range. For this reason, it is desirable to add a component of several kHz or more as a high-frequency extension component. To make the effect easy to understand (so as not to be buried in the original component), add a strong one. Since the band is slightly narrow, DRC is applied to a medium level. That is,
High side component added -3dB
Low side component added -3dB
During DRC.

When the video resolution is 720p, as shown in FIG. 3D, the audio frequency characteristic is also an extension up to around 16 kHz in the high sound range. Even when the resolution is increased, in the case of Internet content, the bandwidth of audio data is often limited. For this reason, as in the case of the resolution of 480p, it is desirable to extend and add a component of several kHz or more as a high-frequency extension component. To make the effect easy to understand (so as not to be buried in the original component), add a strong one. Since the band is slightly narrow, DRC is applied to a medium level. That is,
High side component added -3dB
Low side component added -3dB
During DRC.

  In addition, attribute information (property) is written in a moving image to be distributed by streaming or a moving image file stored in a recording medium. Therefore, the decoder 26 determines the content of decoding processing based on the attribute information and performs decoding. Do. At the same time, this attribute information is sent to the controller 10 and used to determine the processing contents of the video processing unit 11 and the audio processing unit 12.

  FIG. 4 is a flowchart showing the operation of the decoder 26. This operation indicates an operation when a streaming video is input via the network. When a streaming video is input (S20), the video and audio of this operation are analyzed (S21, S22). This analysis is performed by reading the attribute information of the moving image. In video analysis, attributes such as a compression algorithm, resolution, number of color bits, and frame rate are read. In speech analysis, attributes such as a compression algorithm, a sample rate, a bit rate, and the number of sample bits are read out. The attribute information that is the analysis result is transmitted to the controller 10. The controller 10 transfers the video analysis result to the video processing unit 11, determines the content of the audio processing based on the audio analysis result, and sets the audio processing unit 12. The decoder 26 starts decoding the moving image based on the acquired attribute information (S24).

  In this case, the video processing unit 11 may determine the processing content of the video using the analysis result by the video analysis unit 11A in addition to the attribute information transferred from the controller 10. In addition to the attribute information acquired from the decoder 26, the controller 10 may further determine the audio processing content using the video analysis result acquired from the video processing unit 11.

  If the controller 10 cannot acquire the attribute information of the moving image from the decoder 26, that is, if the decoder 26 is not configured to output the attribute information to the outside, the moving image may be decoded and reproduced by the decoder 26. The processing unit 11 may analyze the video and determine the processing content of the video and audio.

  If the audio bit rate is found from the attribute information acquired by the decoder 26, the following processing may be performed.

When the audio bit rate is 32 kbps, as shown in FIG. 5 (A), the audio frequency characteristic extends only to around 6 kHz, and an emphasizable treble band is hardly detected. For this reason, expansion is desirable only on the low frequency side. The original components (quantization noise, etc.) are suppressed and added to the eyes so that they do not stand out. Since the band is narrow and the sound pressure balance is broken, the dynamic range compression processing (DRC) is strongly applied. That is,
High frequency component added None Low frequency component added -6dB
DRC strong.

When the audio bit rate is 64 kbps, as shown in FIG. 5B, the audio frequency characteristic extends to around 10 kHz in the high sound range. For this reason, it is desirable to add a component of several kHz or more as a high-frequency extension component. The original components (quantization noise, etc.) are suppressed and added to the eyes so that they do not stand out. Since the band is narrow and the sound pressure balance is broken, the DRC is put stronger. That is,
High frequency component added -6dB
Low side component added -6dB
DRC strong.

When the audio bit rate is 128 kbps, as shown in FIG. 5C, the audio frequency characteristic extends to around 16 kHz in the high sound range. For this reason, it is desirable to add a component of several kHz or more as a high-frequency extension component. To make the effect easy to understand (so as not to be buried in the original component), add a strong one. Since the band is slightly narrow, DRC is applied to a medium level. That is,
High side component added -3dB
Low side component added -3dB
During DRC.

When the audio bit rate is 256 kbps, as shown in FIG. 5D, the audio frequency characteristic extends to around 18 kHz in the high sound range. For this reason, it is desirable to add a component of several kHz or more as a high-frequency extension component. To make the effect easy to understand (so as not to be buried in the original component), add a strong one. Since the bandwidth is wide, the DRC is weakened. That is,
High frequency component added 0dB
Low band side component addition 0dB
DRC is weak.

When the bit rate of sound is no loss (for example, 1500 kbps), as shown in FIG. 5 (E), the sound frequency characteristic extends to the vicinity of the Nyquist frequency (for example, 22 kHz). Thus, since there is no frequency loss, high-frequency extension processing is unnecessary. Also, since there is no disruption of the sound pressure balance, DRC is unnecessary.
High-frequency component added None Low-frequency component added None DRC None.

  The following estimation is also possible based on the attribute information obtained from the decoder 26. Videos with special resolutions (such as aspect ratios not 16: 9 or 4: 3) and videos with special frame rates such as 15 fps can be processed with a personal computer, etc. Therefore, the audio bit rate may be regarded as low.

  Note that even if the audio bit rate of the attribute information is high, it may be compressed and expanded, so the sound quality is determined from the frequency characteristics regardless of the bit rate, and optimal audio processing is performed based on this The contents of may be determined.

  As described above, the television receiver 1 has been described as an embodiment, but the device to which the present invention is applied is not limited to the television receiver. For example, the present invention can be applied to an AV amplifier having a moving image processing function.

  FIG. 6 shows a block diagram of an AV amplifier 2 which is another embodiment of the present invention. In the figure, the same components as those of the television receiver 1 shown in FIG. The AV amplifier 2 also has a terminal for inputting an audio source, but in this figure, only a terminal for inputting a moving image, that is, an AV source is shown. The selector 20 includes a USB reproduction unit 27 and a LAN communication unit 28 in addition to the HDMI input unit 24 and the analog input unit 25.

  Further, an HDMI output unit 17 is connected to the video processing unit 11. An external television receiver 3 is connected to the HDMI output unit 17. The video output from the video processing unit 11 is sent to the television receiver 3 via the HDMI output unit 17 and displayed on the screen of the television receiver 3. A speaker terminal 18 is connected to the sound emission processing unit (amplifier) 14. An external speaker 4 is connected to the speaker terminal 18. The sound output from the sound emission processing unit 14 is sent to the speaker 4 via the speaker terminal 18 and is emitted from the speaker 4.

  The USB playback unit 27 includes a USB interface and is connected to a recording medium in which a moving image file is stored. The USB playback unit 27 reads out, decodes and plays back the moving image file stored in the recording medium. In other words, the USB playback unit 27 includes a decoder. The USB playback unit 27 transfers the attribute information of the moving image file read by the decoder to the controller 10. In addition, the LAN communication unit 28 receives a moving image that is stream-distributed via a network, decodes this, and reproduces uncompressed video and audio. That is, the LAN communication unit 28 includes a decoder. The LAN communication unit 28 transfers the attribute information of the moving image file read by the decoder to the controller 10. Note that the USB playback unit 27 and the LAN communication unit 28 may share a decoder (CODEC) as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Television receiver 10 Controller 11 Video processing part 11A Video analysis part 12 Audio | voice processing part 26 Decoder 2 AV amplifier

Claims (4)

A content playback apparatus that inputs and plays back audio of a predetermined bit rate,
A bit rate detector for detecting the bit rate of the audio;
An audio processing unit that compresses the dynamic range of the audio and complements high-frequency components, to the extent corresponding to the detected bit rate;
With
The voice processing unit increases the degree of compression of the dynamic range and increases the degree of complementation of the high frequency range component as the bit rate of the voice increases, and decreases the dynamic range as the bit rate of the voice decreases. A content playback apparatus that increases the degree of compression and reduces the degree of complementation of the high-frequency component. The audio processing unit does not perform compression of the dynamic range and complement of the high-frequency component for the audio when the detected bit rate is a size that does not cause loss to the audio. Item 2. A content playback apparatus according to Item 1. Inputting and playing audio of a predetermined bit rate; and
A bit rate detecting step for detecting the bit rate of the voice;
Extent in accordance with the detected bit rate, the audio processing step of performing a complementary compression and treble components of the dynamic range of the audio,
Have
In the sound processing step, the higher the bit rate of the sound, the smaller the degree of compression of the dynamic range, and the greater the degree of complementation of the high-frequency component, and the lower the bit rate of the sound, A content processing method in which a degree of compression is increased and a degree of complementation of the high-frequency component is reduced.   The content processing method according to claim 3, wherein the audio processing step is not performed when the bit rate detected by the bit rate detection step is a magnitude that does not cause loss to the audio.

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