[Libquicktime-devel] libquicktime created files have 0 frame count

[Steven S. <sch...@gm...>]

I tried posting this a few days ago but with a screenshot of the atom
layout the mail item was too large and is waiting for moderator approval.

It's been a little while since I needed to create a 4:2:2 uncompressed
Quicktime file but now when I run the program that did this task in the
past the file shows up as having 0 frames which makes many applications
unhappy.

I've finally narrowed the problem down to the 'stts' atom having a
'sample_count' value of 0.

Attached is a simple test case that produces a 10 frame Quicktime file
named testing.mov.  Compilation was done with cc -I/usr/local/include/lqt
testqt.c -lquicktime but if you've libquicktime installed elsewhere change
the -I and / or add -L.

Running the program as ./a.out results in the file

[larry:~] sms% ls -l testing.mov
-rw-r--r--  1 sms  staff  6759228 Oct 17 16:56 testing.mov

qtinfo says the file has 0 frames

qtinfo testing.mov

Type: Quicktime
  0 audio tracks.
  1 video tracks.
    704x480, depth 24
    rate 23.976025 [24000:0] constant
    length 0 frames
    compressor 2vuy.
    Native colormodel:  Undefined
    Interlace mode:     None (Progressive)
    Pixel aspect ratio: 10:11
    No timecodes available
    supported.
  0 text tracks.

and the frame rate doesn't look right either, I'd expect [24000:1001].   I
thought too that the Native colormodel should be 422.

Also attached is a small extract  of 'dumpster' (an Apple utility that is
very useful for exploring Quicktime files and can also edit/modify them)

Note the 'stts' atom has a 0 for the 'sampCnt' (sample_count) field.  If I
change that to 10 the qtinfo output is  correct.

The test program is based on the y4mtoqt program from mjpegtools.  Y4mtoqt
was working for years and hasn't changed, so something in libquicktime's
been broken in the last few months.

decoding existing files created earlier or imported from a video capture
works but at the moment libquicktime can't be used to create new files that
other applications are happy with.

Steven Schultz