[FFmpeg-devel] [PATCH] Dump info for all streams (not just those known to be in a program)

[Måns Rullgård]

Wolfram Gloger <wmglo at dent.med.uni-muenchen.de> writes:

>> From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans at mansr.com>
>> 
>> "Sane defaults" are not appropriate here.  If it is not MPEG, and
>> nowadays this is quite likely, your defaults will be completely
>> *wrong*.
>
> We've been through this before, I can only state that I disagree.

Fortunately I have others on my side.

>> > Even when just choosing "stream copy" stream parameters (including
>> > codec id) are later adjusted by the mpeg parser.
>> 
>> You apparently don't know enough about how FFmpeg works, because this
>> statement is plain wrong.
>
> I stand by that statement.  Fortunately the existence proof
> is easy:
>
> % ~/ffmpeg/ffmpeg-wg/ffmpeg_g -i DVBS-11-09-23-53.ts
> Input #0, mpegts, from 'DVBS-11-09-23-53.ts':
>   Duration: 01:30:59.4, start: 21920.089456, bitrate: 7246 kb/s
>   Program 28006 
>   Program 28011 
>   Program 28014 
>   Program 28016 
>   Program 28007 
>   Program 28008 
>   Program 28017 
>   Program 28012 
>   Program 28013 
>   Other
>     Stream #0.0[0xe1]: Audio: liba52, 48000 Hz, stereo, 384 kb/s
>     Stream #0.1[0xd2]: Video: mpeg2video, yuv420p, 720x576 [PAR 16:15 DAR 4:3], 15000 kb/s, 25.00 fps(r)
>     Stream #0.2[0xdc]: Audio: mp2, 48000 Hz, stereo, 256 kb/s
>
> Note the "mpeg2video".  If the "default" case in new_pes_av_stream()
> would have been the only assignment to codec_id, it would wrongly read
> "mpeg1video".  But I'm sure you're going to tell me that this effect
> is also unintended and "wrong".

You are mistaken.  In FFmpeg, mpeg1video and mpeg2video decoders are
the same.  Nothing will fix the codec setting if it isn't MPEG at all,
but rather, say, H.264.

>> If it is not MPEG, you will get garbage.  How is that better than not
>> getting anything at all?
>
> If it is not MPEG, I don't get anything at all, just an error
> message.  This is fine with me.

Well, that's not fine with me or a lot of other people.

-- 
M?ns Rullg?rd
mans at mansr.com