[FFmpeg-devel] Support for generating avm2 compatible swf files

Stefano Sabatini stefano.sabatini-lala
Wed Jan 16 09:42:46 CET 2008

On date Tuesday 2008-01-15 12:05:26 +0100, Baptiste Coudurier encoded:
> Hi,
> Stefano Sabatini wrote:
> > On date Tuesday 2008-01-15 11:04:59 +0100, Baptiste Coudurier encoded:
> >> Hi
> >>
> >> Michael Niedermayer wrote:
> >>> On Tue, Jan 08, 2008 at 10:20:39AM -0800, Paul Egan wrote:
> >>>> When working with Flash 9/Flex the AVM2 runtime sandboxes
> >>>> any swf files of older versions.  
> >>> ?
> >>>
> >>>
> >>>> This means you can't
> >>>> currently control the timeline of any swfs generated by
> >>>> ffmpeg.   Attached is a little patch to extend the ffmpeg
> >>>> swf support with a new file format, "avm2", which can be
> >>>> loaded into a Flash 9/Flex application.
> >>> adding a new dummy format for every little changed parameter is not acceptable
> >> I tend to agree here, though we got some dummy formats like 3g2, and Im
> >> thinking about a "flavour"/"brand"/"version" (people please say
> >> whichever you prefer or suggest a better one) field to AVFormatContext,
> >> which could be used for swf and or mp4/3gp (ftyp).
> >>
> >> What do you think about that ?
> > [...]
> > 
> > Also I would like something similiar for every AV stream format
> > for which is supported encoding or decoding, to be displayed for
> > example with ffmpeg -formats, showing a more verbose description of
> > it, similiar to the long_name field of AV{Input,Output}Format.
> > 
> > For example:
> > flv -> Flash Video Codec
> > wmv1 -> Windows Media Video Codec version X
> > H264 -> H264 aka Advanced Video Codec aka AVC aka JVC aka Mpeg4 part 10
> > 
> > Also libavformat solution is not ideal since it requires to define
> > such field for both muxer and demuxer, and is prone to
> > inconsistencies.
> > 
> > A better idea would be to create a new structure for every
> > AV stream format identified by an id, containing this description,
> > referenced by both encoder(s) and decoder(s).
> > 
> > What do you guys think about it?
> Which problem are you addressing here ? I don't really see.

Application example: the user is grepping for windows media codecs in
the -formats output, but only the string "wmv" is showed, or the user
is grepping for AVC but only h264 is reported in the -formats
output. To me would be nice to deliver to applications/users more
verbose information regarding the supported AVT stream formats.
> I don't think what you propose has anything related to the swf version
> problem.

True, forgive me I haven't enough energy to start a new thread, but I
wanted to check if that was interest between devs regarding this
feature request.
> Furthermore, what are you refering to with "AV stream format" ? It would
> be more AVStream in libavformat, or AVCodec in libavcodec maybe ?

With "AV stream format" I meant a "monomedial" (A/V/textual) stream
format, encoded/decoded by codecs, as opposed to a multimedia stream
format multiplexed/demultiplexed by muxers/demuxers.

Since a codec manages a "monomedial stream format", and theoretically
ffmpeg may support more than one codec for every such format, then a
codec should refer to some structure describing the format identified
by a unique id, containing also information such as the "long_name".

Stefano Sabatini
Linux user number 337176 (see http://counter.li.org)

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