H.264/AVC DeMux using Haali Media Splitter

[docfraggler]

i'm currently trying to demux an .mp4 using a graphedit, haali and a dumper filter. everything works as expected to this point - i have some type of avc1 raw stream on my harddisk. :) unfortunately it looks like the picture start code sequence (0x000001) is damaged for most of the frames in this file, so no further processing of this data is possible :eek:

i tried a few other source/splitter combination like gabest or nero, but all of them reproduce exactly the same binary stream . why the hell i can't get proper frame-syncs out of this process ? :mad: btw. i don't like to do it using mp4creator or ffmpeg.

any advisory ? :thanks:


regards, docfraggler

[mediator]

avc samples in mp4-files don't use startcodes. Additionally, Sequence Parameter Set and Picture Parameter Set are transmitted via the filter connection mediatype rather than the mediasamples.

To put it short: You don't get a usable AVC bytestream with this procedure.

You need to use something that applies the necessary conversion from AVC in MP4 to AVC bytestream. Probably it's worth to have a look on MP4Box.

[docfraggler]

i know about the sps and pps issue but thats a problem which can be fixed in my application if neccessary.

additionally i tried a demux with mpeg4 creator (which works great) it gave me nearly exactly (!) the same binary output stream (except the sps and pps bytes) as the haali/dumper filter chain. the generated output has the same length, it has the same data in it. the only exceptions are two bytes for each frame (which damage the psc)

can anybody explain to me what type of information is transmitted using these bytes ?


cheers, docfraggler

[mediator]

the size of the next NAL unit

[docfraggler]

thank you mediator. i finally got it. the guys at msdn (http://msdn.microsoft.com/en-us/library/dd757808%28VS.85%29.aspx) had an explanation handy too.

cheers, docfraggler