[FFmpeg-user] framemd5 for audio?

David Rice daverice at mac.com
Wed Aug 8 01:29:32 CEST 2012

On Aug 7, 2012, at 7:14 PM, Paul B Mahol wrote:

> On 8/7/12, Peter B. <pb at das-werkstatt.com> wrote:
>> Hello,
>> I'm a big fan of the framemd5 functionality for verifying losslessness :)
>> Unfortunately, it doesn't work for checking the audio.
>> I presume it's related to how the audio data is distributed among the
>> frames?
> For stuff that you compare they must have same number of samples in every frame.
>> Is there any way to have framemd5 work correctly on audio, too?
> There is md5. The only way to make framemd5 output same is to make
> both compared codecs output frames of same size - which is not possible.
> But you could use intermediate format/codec instead....

One issue here is that while there is rawvideo for framemd5 of video streams, there is no equivalent rawaudio format for audio data. The framemd5 of audio will be applied to signed 16 bit raw audio (even if the source is unsigned or >16 bit). So for >16 bit audio the framemd5 process wouldn't work for losslessness verification since the bit depth would need to be changed prior to the application of the checksum.
Dave Rice

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