[Ffmpeg-devel] Re: [PATCH] DVCPRO50 support

[Måns Rullgård]

Baptiste COUDURIER said:
> M?ns Rullg?rd wrote:
>> Baptiste COUDURIER said:
>>
>> [...]
>>>
>>> If I want to fix movenc.c to properly set fourcc, I need to check
>>>pix_fmt and bitrate and even resolution or framerate, while a different
>>>codec_id would make me only check for resolution or framerate.
>>
>>
>> The need for separate codec tags is a peculiarity of mov, not of the codec.
>> What if some container made the same requirement for MPEG?  Encodings
>> covered by the same specification, and handled by the same code, should
>> use the same codec_id.
>>
>
> Well, ISO/MPEG group now use ISO Media format, which is MOV evolution so
> expect this behaviour in the future for every new codec (JPEG 2000 is
> ISO Media based). What is your opinion ? IMHO making muxers a big mess
> is not a good idea.

The ISO 14496-12/14/15 *is* a mess.  Our best hope now is to contain it
and pray it doesn't escape.

> They do not share parameters (different bitrates, different pixel
> formats) and in `industry` (ISO, MPEG, SMPTE) that means oftenly
> different specifications (for DV it IS the case), thats why they do have
> different names. I agree that systems should be able to detect streams,
> but embedded Hardware is not designed that way.

I don't know DV, so forgive me if I've made some incorrect assumption.  I
was of the impression that all the DV formats were basically the same, with
minor variations in parameters, similar to MPEG being capable of encoding
different pixel formats, interlaced/progressive etc.

> Mpeg2 has profile parameter, to design 422 etc. If you mess with that
> your stream wont play on broadcast servers.

The profile parameter is part of the video elementary stream, not the
container.  All streams encoded encording to ISO 13818-2 use the same
codec ID in program/transport streams.

-- 
M?ns Rullg?rd
mru at inprovide.com