I´m working on an application based on directshow that has to convert an AVI source file to to an mp4-file that can be played back with Quicktime.
Since 3ivx, according to my web research the most popular way to fulfill this task, has become commercial (and my budget is quite limited), I decided to use a solution based on ffdshow.
I created a simple graph in graphedit, using LAME for audio encoding and GDCL MPEG 4 Multiplexor for the muxing, but everytime I try to play the movie with Quicktime, I´m getting an error indicating a wrong "sample description". Playback with Windows Media Player is working, except that there is no sound.
My guess is that there´s a problem with the muxer, because every time I try to add audio encoding, graphedit automatically adds an decoder after the encoding unit (see picture link).
http://imageshack.us/photo/my-images/39/graphjrgr.png/
Any ideas on how to integrate ffdshow in a better way, tips for alternative mp4 muxers, or a complete different approach are appreciated!
The GDCL muxer has limited number of audio formats that it supports, probably you should check the source code for the muxer to see if the formats you are using are in fact supported. Basically, you need to choose an audio encoder that the mux recognizes as valid. It might be possible to use GraphEdit to choose different properties for the encoder filter that allow things to work better.
I have had some luck with the Monogram x264(video) and AAC(audio) encoders. See http://blog.monogram.sk/janos/directshow-filters/
Finally, try the debug version of the GDCL mp4 muxer.
Also, you must be aware of MPEG-4 LA licensing requirements for x264 http://www.mpegla.com/main/programs/AVC/Pages/FAQ.aspx