[Ffmpeg-devel] Temp data file inside libavformat

Patrick Roberts proberts9999
Fri Nov 25 23:00:52 CET 2005

--- M???ns Rullg???rd <mru at inprovide.com> wrote:

> Patrick Roberts <proberts9999 at yahoo.com> writes:
>> Is there any existing libavformat example for
>> using a temp data file when writing?  I didn't find
>> anything by grep'ing the source.  (There does seem
>> to be an example in libavcodec.)
>>   If anyone is interested in why or offering
>> suggestions:  The reason I'm asking is I'm adding
>> libavformat/movenc.c support for streaming 3GP and
>> MP4, and the mdat atom (actual movie data) is
>> currently written before the moov data (movie
>> info). The moov data depends on values generated
>> when the packet pump calls write_packet, which
>> writes the mdat data.  For streaming, the mdat
>> atom needs to come after the moov atom.  I could
>> write an external tool to run on the
>> 3gp file, but I'd

> Isn't that what the qt-faststart tool included with
> ffmpeg does?

  It looks like that's what it's supposed to do for
quicktime files, but it doesn't work for 3GP and MP4
files.  (Plus there are other streaming considerations
for 3GP and MP4 files like hint tracks.)  Rather than
modding it or writing a new, separate tool, I'd rather
add the functionality directly into libavformat as it
could later be used for direct streaming.  (i.e.
instead of an output file, specificy a device or pipe
capable of processing a 3GP or MP4 stream)


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