[x264-devel] Bug in mp4 header ?

[Trahald]

On Wednesday, November 24, 2010, TW <tw at halbritter.org> wrote:
> Hi, I convert movies using MeGUI for a long time. I convert different type of sources to 1280 x 720 mp4 which I can use on iPad, iPhone and PS3. I found out, that the Quicktime player for Windows is a good test vehicle for verifying the converted movies. If it works on Quicktime player it works also at PS3 and the other devices.If the source is a movie with a frame rate of 23.976 fps the converted mp4 always causes an error -2002 on Quicktime player and I get also an error on PS3.I did a little bit of research and found out, that the mp4 header of the movie has wrong entries in the Media Handler Header (mdhd). The attachment shows two examples. For my opinion the values for stts.sampCnt and  stts.sampDur were defined improper, so that product of these two values exceeds the allowed range of 32 bit in the mdhd structure. It can be shown, that any part of a movie with 23,976 fps, which must not be longer than 28 min, has correct entries in the header and can be played without problems. If the part is longer than 28 min the error occurs. (MeGUI 0.3.5.0 with x264 r1649)Please inform me, if you need some more information. Best regards Thomas

You must ensure the fps is actually 23.976. The best way is to specify
fps as 24000/1001. I think it has more to do with the new input
filters revealing issues in the source than any changes to the mp4
code.