[FFmpeg-devel] [PATCH] avformat/mpegenc - reject unsupported audio streams

[Carl Eugen Hoyos]

> Am 19.07.2019 um 12:44 schrieb Gyan <ffmpeg at gyani.pro>:
> 
> 
> 
>> On 17-07-2019 02:23 PM, Carl Eugen Hoyos wrote:
>> 
>> 
>>> Am 08.07.2019 um 14:05 schrieb Gyan <ffmpeg at gyani.pro>:
>>> 
>>> 
>>> 
>>>> On 25-04-2019 01:48 PM, Gyan wrote:
>>>> 
>>>> 
>>>>> On 25-04-2019 01:23 PM, Ali KIZIL wrote:
>>>>> 
>>>>> There are also Dolby Codecs (ac3 & eac3). Will it also throw error for
>>>>> these codecs ?
>>>> AC3   is      supported before and after this patch.
>>>> EAC3 is unsupported before and after this patch.
>>>> 
>>>> But it's sent to the same decoder, so support could be added. I'll check.
>>> Attached patch allows muxing EAC3 in MPEG-PS.  Stock ffmpeg can demux and decode such streams fine.
>> Which descriptor is used for eac3?
>> Please do not commit just because decoding works with FFmpeg, at least try to find some specification.
> 
> The PS muxer appears to use System A and this is what the ATSC A/52 (2012) standard says,
> 
> "For System A, this section extends the use ofthe AC-3 Registration Descriptor defined in Section A3 in combination with the E-AC-3 stream_type value defined below."
> 
> and
> 
> "E-AC-3 bit streams shall be identified with a stream_typevalue of 0x87 when transmitted as PES streams conforming to ATSC-published standards."
> 
> Note that the stream_type value of AC-3 is 0x81 yet our id sequence starts from 0x80.  This patch uses the same descriptor series as AC-3, however if I switch to 0x87, only one such stream may be muxed as 0x88 was assigned (by you) to DTS. Also, our demuxer sets the codec_id to DTS for 0x88 to 0x8f.
> 
> Both stock ffmpeg and VlC 4.0 nightly play files using the current patch. Mediainfo also identifies the codec correctly.
> 
> Comments?

Did you test with WMP or QT?

Carl Eugen