[XviD-devel] Custom Quantization MPEG-4 compatiblily issue?

[Christoph Lampert]

On Wed, 15 Jan 2003, suxen_drol wrote:
> > Does XVID do this somehow in a non-standard way?
> 
> just gave it a try (mp4creator -create=custom.avi custom.mp4), and i
> i got a similar error: MP4ERROR: MP4WriteCountedString: Result too large
> 
> the error occurs in the following function:
> void MP4File::WriteCountedString(char* string, 
> 	u_int8_t charSize, bool allowExpandedCount)
> this writes out a string of bytes. the above error is generated when
> allowExpandedCount=false and the charSize (string length) exceeds 255
> bytes.
> 
> i modified the function to dump the string:
> 
> custom.avi(custom mpeg qmatrix): charSize=332 bytes: (VOL=171 bytes)
> data:application/mpeg4-od-au;base64,AYCAgVcBgICBUgUfA4CAgUsAAQAEgICBPSARAGBhABXrQAAMNSsFgICBKwAAAbADAAABtQsAAAEAAAABIAAGxABnDEwQgFMIEBAQEBAQEBAQERAREBESERISERIVExQVFBMVGBYWGBgWFhgZGRseGxkZHR8jIx8dGiksKSQvNjYvQUZBWFhzigoKCgoKCgoKCgqKCooKi4sLCwsLjQwMDQwMDQ8NjY8PDY2PEA+REpEPkBITFhYTEhYZnBmWHaIiHaisKLa2yGMAAAGyWHZpRDAwMDh/AAaAgIABAA==
> 
> default.avi(default mpeg qmatrix): charSize=160 bytes: (VOL=43 bytes)
> data:application/mpeg4-od-au;base64,AYCAgFcBgICAUgUfA4CAgEsAAQAEgICAPSARAFZ4ABjMAAANbdsFgICAKwAAAbADAAABtQsAAAEAAAABIAAGxABnDEwQgFJjAAABslh2aUQwMDA4fwAGgICAAQA=
> 
> both .avis are of similar size; so it seems the charSize is relative to
> the length of the VOL. thus large VOLs cause mp4creator to fail.

Hm, so does the custom quant matrix AVI file play with ffmpeg? Because
transcode segfaults when trying to use custom quant matrices, so I
couldn't test it. But maybe that's my fault. 

gruel