[FFmpeg-devel] TrueHD track in EVO not playable/testable with ffplay

[Justin Ruggles]

Ramiro Polla wrote:
> 2009/7/9 M?ns Rullg?rd <mans at mansr.com>:
>> Michael Niedermayer <michaelni at gmx.at> writes:
>>> On Wed, Jul 08, 2009 at 11:01:57PM -0700, Baptiste Coudurier wrote:
>>>> On 07/08/2009 07:47 PM, Michael Niedermayer wrote:
>>>>> my tired mind says we need a
>>>>> coded_channels representing the number of channels stored in the stream
>>>>> and a seperate field that represents the decoder output channels
>>>> I suggest to keep ->channels as the coded channels and to use another field
>>>> like output_channels.
> 
> Wouldn't this break API? Programs currently check avctx->channels to
> know how much data there is. If we make them check
> avctx->output_channels we'd need to bump major (and break something
> else so people know they need to update and we hope they stumble upon
> a place that explains this change too).
> 
>>> I wouldnt mind, if we wouldnt have
>>> coded_width & coded_height in there
>> This is different.  Unless I am mistaken, coded_width and coded_height
>> indicate the encoded width/height of a video including any padding
>> (e.g. mod-16) required by the codec but never meant to be displayed.
>>
>> In the case at hand, we have a number of audio channels, all of which
>> are meaningful, but which may be downmixed before output.
> 
> By looking at the doxy in avcodec.h I don't think coded_ is the best too.
> 
> I attached a patch to see if this is what you mean by adding a new
> field (I named it coded_channels like michael suggested but I don't
> really like the name as I pointed out).
> 
> Now would this mean that all decoders should be changed to
> "avctx->coded_channels = avctx->channels = <number of channels>"? Or
> only the decoders that support downmixing (and the documentation
> should be updated to say this field only has meaning if it's != 0)?

This would affect demuxers as well if they rely on a parser.
av_find_stream_info() expects the parser to set avctx->channels or else
it will start trying to decode frames.

-Justin