Problems demuxing mp4 file...

[SirCanealot]

Hi all.
I was recently sent an mp4 file took directly from a digital camera (doesn't look half bad either... MPEG4, 640x@2mbits...), and I was asked to recompress it, and see what file size I can get it down to using cleanup filters/XVid etc.
Only I have a few problems...
Of course, VD doesn't seem to want to open MP4 files, so I found MP4UI and tried that. I demuxed the AAC audio fine, and the video seemed to be demuxed fine, however: when I try to play it, the media player plays the video ZOOMED to 320x240. FFDShow reports the video is 320x240, but this is simply not true: it is 640x480!
It gets a little odder, as I can add boarders with FFDShow, or resize to 640x480 to get the original screen size back - but I'd prefer a real solution, especially if I'm going to be recompressing it.
I tried opening the demuxed AVI in VirtualDubMod too, and it just crashed...

So, does anyone have any ideas?
Thanks a lot.

[stephanV]

uhm... AFAIK MP4UI doesnt remux the files in the AVI-container, it just saves the elementary video stream... so you cant open that in VD(M) for obvious reasons.

why not try to frameserve the MP4 file via AVIsynth's directshowsource, encode a video only AVI and remux the videostream from the AVI with the audio stream from the original MP4 using e.g. 3ivx-muxer in graphedit.

[hans-jürgen]

Originally posted by SirCanealot
when I try to play it, the media player plays the video ZOOMED to 320x240. FFDShow reports the video is 320x240, but this is simply not true: it is 640x480! That's a common problem with the MP4 videos produced by digicams like Sanyo Xacti and Olympus C-770 at the moment. See the GPAC forum for a method how to work around that issue with MP4Box, their file muxer:

http://sourceforge.net/forum/message.php?msg_id=2603886

[bond]

hans-jürgen is right PLUS the video stream in .mp4 is mpeg-4 already, which means its heavily compressed already and therefore it doesnt really make sense to reencode it with xvid (which is mpeg-4 too)

[SirCanealot]

That's a common problem with the MP4 videos produced by digicams like Sanyo Xacti and Olympus C-770 at the moment. See the GPAC forum for a method how to work around that issue with MP4Box, their file muxer:

I've look through the associated sites, but I'm still kinda at a miss what to do.
I tried this(as recomended in the thread on audiocoding.com):
Open the file in graphedit
Do 3Ivx Media Splitter
Do 3Ivx Media Muxer
Do File Writer to MP4

And was left with the exact same problem...
Sorry, but if the fix has been giving, can you spell it out for me? ^^
I tried looking for this "MP4Box" on google, but aparently it's not up for download any more :/

why not try to frameserve the MP4 file via AVIsynth's directshowsource, encode a video only AVI and remux the videostream from the AVI with the audio stream from the original MP4 using e.g. 3ivx-muxer in graphedit.

That's what I tried to do next, but I got an even weirder problem.
Every time I open up the .avs, say - frame 300 will be different :/
I can't even seem to find the same frame by scrolling through the frames. I don't really know how to explain it - it is very odd...

hans-jürgen is right PLUS the video stream in .mp4 is mpeg-4 already, which means its heavily compressed already and therefore it doesnt really make sense to reencode it with xvid (which is mpeg-4 too)

Me and my mighty XVid can compress it better than a poncy Digicam :D
No, really. For its purpose file size is all important, so the smaller I can get it, the better...

Thanks for your help all...

[bond]

Originally posted by SirCanealot
Sorry, but if the fix has been giving, can you spell it out for me?well hans-jürgen already linked to the explanation:

"this is a common issue with some mp4 tools (they use a fix 320x240 size for visual tracks when creating files).
I'll fix the AVI export to ignore the visual track size indicated in mp4 and use the visual stream size.

Meanwhile you can try to export to avi (-avi) then reimport from avi (-import file.avi#video), then finally re-export. This should work as the avi importer ignores AVI video size."

I tried looking for this "MP4Box" on google, but aparently it's not up for download any moretoo lazy to use the search function of the forum?

Me and my mighty XVid can compress it better than a poncy Digicam :Dwell i hope you know that you will loose quality for sure if you do so

[SirCanealot]

I managed to find a version of MP4box searching the forums. Sorry - the google links I found said that the software was not avalible freely anymore, so I assumed Doom9 would not allow what I thought was commercial software to go around.

I tried doing a -avi with mp4box (god, I hate command line), but it came back with "Error opening file: Cannot open the requested URL"
*sigh*
Am I just going to have to wait for a version of mp4ui that fixes this error?

And yes, I'm fully aware that I'll lose quality, but the point is to minimise it, right? :D

[bond]

Originally posted by SirCanealot
I tried doing a -avi with mp4box (god, I hate command line), but it came back with "Error opening file: Cannot open the requested URL"you didnt specify the correct paths to your files (use search for finding some sample commandlines for mp4box)