This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-338205, filed Dec. 27, 2007, the entire contents of which are incorporated herein by reference.
1. Field
One embodiment of the present invention relates to an audio data processing apparatus and an audio data processing method which process audio data including a watermark that enables a copyright holder to be identified.
2. Description of the Related Art
In recent years, the importance of copyright protection has been increasing as high-capacity optical disks, such as DVDs, have become widely used. The technique for limiting the transfer of content on the basis of the copyright protection information recorded on an optical disk is known (e.g., refer to Jpn. Pat. Appln. KOKAI Publication No. 2005-92943).
Presently, of the commercially-available HD DVD content, the application of a watermark, or an electronic watermark that enables a copyright holder to be identified, is under consideration for those protected by the high-capacity optical disk device copyright protection standard (AACS). In this connection, a DVD player capable of detecting a watermark and providing reproduction control on the basis of the detection result is being developed. The watermark has to be detected from the result of expanding audio data by PCM decoding.
Many of the existing DVD players are also compatible with digital audio output, such as the High-Definition Multimedia Interface (HDMI). In the future, a DVD player which is compatible only with an HDMI audio output and has no audio output terminal excluding HDMI terminals is expected to appear on the market.
When the watermark is detected with a DVD player compatible with HDMI digital audio outputs, even if compressed audio data is output in HDMI form, the audio data has to be decoded to detect a watermark. If an AV amplifier which has the function of detecting a watermark comes on the market, the DVD player has to decode the audio data because it is unknown if an external unit, such as an AV amplifier, actually connected to the DVD player has a watermark detection function. In this case, since a reduction in the load in processing audio data cannot be expected, this makes it difficult to construct an inexpensive system.
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings.
According to one embodiment of the invention, there is provided an audio data processing apparatus comprising: a selection unit which selects audio data to be reproduced under copyright protection; a digital output interface unit which outputs the audio data selected by the selection unit in the form of a bitstream to an external device connected via a dedicated cable; and a control unit which acquires specification identification data from the external device before the bitstream output of the audio data and recognizes a watermark detection function of the external device on the basis of the specification identification data.
According to one embodiment of the invention, there is provided an audio data processing method of selecting audio data under copyright protection and causing a digital output interface unit to output the selected audio data in the form of a bitstream to an external device connected to the digital output interface unit via a dedicated cable, the audio data processing method comprising: acquiring specification identification data from the external device before the bitstream output of the audio data and recognizing a watermark detection function of the external device on the basis of the specification identification data.
With the audio data processing apparatus and the audio data processing method, specification identification data is acquired from the external device before the bitstream output of the audio data. Then, the watermark detection function of the external device is recognized on the basis of the specification identification data. Accordingly, since it can be left to the external device to perform decoding necessary to detect a watermark in outputting digital audio, an inexpensive system can be constructed easily by reducing the load in processing audio.
An embodiment according to the invention will be described hereinafter with reference to the accompanying drawings.
Hereinafter, a DVD player according to an embodiment of the invention will be explained.
The audio processing unit 16 includes a decryption unit 16A for decrypting the encrypted audio data, a decode unit 16B for decoding the audio data output from the decryption unit 16A, and a watermark detection unit 16C for detecting a watermark from the audio data output from the decode unit 16B. Unencrypted audio data or audio data successfully decrypted is output from the decryption unit 16A to the decode unit 16B. In the decryption unit 16A, the audio data successfully decrypted is selected as audio data to be reproduced under copyright protection.
When the audio data obtained from the decryption unit 16A has been compressed, the AV amplifier 20 is compatible with the compression method and the detection of watermarks, and the user requests the output of bitstreams, the output of the decryption unit 16A is input to the HDMI unit 17. In this case, the DVD player 10 does not detect a watermark.
When the AV amplifier 20 is compatible with the compression method but is incompatible with watermark detection, the decode unit 16B carries out a decoding process and outputs the resulting audio data, or PCM data, to a watermark detection unit 16C. The watermark detection unit 16C detects a watermark. If the watermark detection unit 16C has detected an unauthorized watermark, the reproduction is stopped. If not, the result of processing at the decode unit 16B is input to the HDMI unit 17, which then outputs the data to the AV amplifier 20.
The system control unit 11 can control the processes performed at the decryption unit 16A, decode unit 16B, and watermark detection unit 16C. The HDMI unit 17 supplies the audio data from the decryption unit 16A and the audio data from the decode unit 16B as a bitstream output and a PCM output to the AV amplifier 20, respectively. The HDMI unit 17 informs the system control unit 11 that an external device (i.e., AV amplifier 20) is connected to the HDMI unit 17 with a dedicated cable (i.e., HDMI cable). As a result, the system control unit 11 recognizes the connection of the AV amplifier 20, acquires specification identification data (EDID) from the AV amplifier 20 before outputting an audio data bitstream, and recognizes at least the watermark detection function of the AV amplifier 20 from the specification identification data. When acquiring the EDID, the HDMI unit 17 is controlled so as to transmit an EDID request to the AV amplifier 20 via the Display Data Channel (DDC) protocol DDC line provided in the HDMI cable and receive an EDID sent back from the AV amplifier 20 via the DDC line in return to the request. The EDID has such a field configuration as can recognize the watermark detection function and the compatible audio data compression method.
If it is determined in step S6 that there is no watermark detection result, or if it is determined in step S7 that it is a proper watermark, a check is made in step S9 to see if the output of the audio data has been completed. If the output of the audio data has not been completed, step S5 is executed again to continue the output of the audio data. If the output of the audio data has been completed, the audio output process is terminated.
Furthermore, if it has been determined in step S3 that there is no watermark detection result or if it has been determined in step S4 that the bitstream output has not been selected, the audio data is inhibited from being output in bitstream form in response to the user's reproduction request in step S10. Then, in step S11, the decode unit 16B decodes the audio data and outputs the decoded data in PCM form to the AV amplifier 20. In step S12, a check is made to see if the watermark detection result from the watermark detection unit 16C is present. If the watermark detection result is present, a check is made in step S13 to see of it is a proper watermark. If it is not a proper watermark, the PCM output is stopped in step S14 and the audio output process is terminated.
Moreover, if it is determined in step S12 that there is no watermark detection result, or if it is determined in step S13 that it is a proper watermark, a check is made in step S15 to see if the output of the audio data has been completed. If the output of the audio data has not been completed, step S11 is executed again to continue the output of the audio data. If the output of the audio data has been completed, the audio output process is terminated.
In the embodiment, the DVD player is configured not to output the analog audio and the digital audio at the same time. Before the bitstream output of the audio data, specification identification data (EDID) is acquired from an external device, that is, the AV amplifier 20, and the watermark detection function of the external device is recognized on the basis of the specification identification data. Accordingly, since it can be left to the external device to perform decoding necessary to detect a watermark when the DVD player provides digital audio output, an inexpensive system can be constructed easily by reducing the load in processing audio data.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2007-338205 | Dec 2007 | JP | national |