Re: [Gnash-dev] Video streaming: manually specify codec

[stefasab]

On date Thursday 2009-07-02 21:02:08 +0200, strk gnashed:
> On Thu, Jul 02, 2009 at 04:25:34PM +0200, Udo Giacomozzi wrote:
> 
> > s> I'm not a media expert, but I've seen at least ffmpeg threating
> > s> formats differently from codecs.
> > 
> > Is "format" a synonym for "container" ?
> 
> Probably. It's something you need a "demuxer" to open ...

Yes, in the FFmpeg jargon a "format" usually refers to a *container*
format, an input format is a demuxer and an output format is a muxer,
and libavformat deals with them (yes this is very confusing as the
term "format" has many different meanings).

> > s> For formats, AS doesn't let you specify anything because it only
> > s> supports FLV. Or am I missing something ?
> > 
> > Not true, you can easily show MPEG streams not embedded in a FLV
> > container using NetStream:
> > 
> > ---- AS CODE -----------------------------------------------------
> > url = /* any URL to a .MPG file or similar */;
> > 
> > var connection_nc:NetConnection = new NetConnection();
> > connection_nc.connect(null);
> > var stream_ns:NetStream = new NetStream(connection_nc);
> > video.attachVideo(stream_ns);
> > 
> > stream_ns.play(url);
> > ---- AS CODE -----------------------------------------------------
> > 
> > In the case of a .mpg file, Gnash/Ffmpeg will correctly detect the
> > container/format/codec. I guess this applies to a lot more formats.
> 
> I'm aware about this "feature" for Gnash (we designed it that way)
> but wasn't aware about the Adobe player allowing it.
> 
> > Probably there is simply no auto-detection for mjpeg available (or why
> > would the command line tool fail?).
> 
> Again, I suggest you ask ffmpeg developers about the "why".
> Maybe it could be fixed in ffmpeg so gnash would just work.

There are some formats (in the sense of "multi-media stream formats")
which can't easily be recognized if the extension of the format name
is not meaningful, since they don't contain metadata/headers, as in
the case when you use the ".jpeg" suffix for an "mjpeg" stream. I
believe MJPEG is such a format.

Regards.