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

[Gyan]

On 19-07-2019 04:14 PM, Gyan wrote:
>
>
> 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?

Carl, ping.

Gyan