[Libquicktime-devel] More patches

[Joseph A. <jo...@mi...>]

Hi,

I've got 3 patches this time.

1. uninitialized_read.patch
Fixes reading uninitialized memory or even (if you are unlucky) invalid 
memory.

2. sdtp_for_xdcam.patch
Fixes a few things that were wrong with my XDCAM encoding code and 
introducing support for sdtp atom. These changes make it possible to 
load XDCAM files generated by libquicktime into Avid Media Composer. One 
interesting thing is Avid 6.5 fails to load XDCAM files with timing of 
1/25, while 24/600 (which is the same) works fine. Avid 5.5 doesn't have 
this problem.
As part of those changes I took libery to unconditionally enable (it was 
#ifdef DO_INTERLACING before) setting AVFrame->interlaced_frame and 
AVFrame->top_field_first according to libquicktime's interlacing 
setting. I didn't enable setting interlaced DCT though, as I prefer 
individual codecs to set this up. That's not a big deal anyway. Now, you 
might think top_field_first is also not a big deal, but that's only if 
you use Windows QuickTime or libquicktime API to decode frames, as 
neither of them support decoding individual fields. Now, I know for sure 
that Avid Media Composer uses Windows QuickTime API to read compressed 
frames but uses it's own decoder to decode them. Therefore, field order 
is important.

3. Fixes a problem with presentation time stamps that get fed into 
ffmpeg. Initially I thought that was a bug in FFMpeg and even sent them 
a patch. In the discussion that followed it became clear it's 
libquicktime's bug, not FFMpeg's one. Here is the discussion on the 
ffmpeg mailing list:
http://comments.gmane.org/gmane.comp.video.ffmpeg.devel/154243
I am not 100% sure this patch won't cause side-effects, such as 
inability to encode variable-length frames, therefore I made it a 
separate patch, rather than including it in the XDCAM patch.


-- 
Joseph Artsimovich
Senior C++ Applications Developer
MirriAd Ltd