> Never-the-less, trying to concat certain files that appear whole and
intact with all I/P/B frames, does cause a couple problems, with several
files, about 10% of the ones I tested.
> The input files used for these tests, can be found at:
>
http://seahorseCorral.org/videos/tests/20141107_4horses-scatter-cows_mini1355.mov
After some needed sleep I thought of some new tests.
Loading #1 in avidemux looks correct. An I frame every 15 frames. Ah,
the 2 frames Are there after all, but they are skipped over in mplayer
because the timing is not 30 fps or something about the joint location.
In avidemux, I frame# 375 is at 12.537 , 390 is at 13.039 but should be
13.000. Each I frame drifts in time by 0.001 or 0.002 seconds. Using the
inquiry function of ffmpeg reveals the problem.
> ffmpeg -i 20141107_test1-loses2frames.mov
ffmpeg version N-68279-g72c9844 Copyright (c) 2000-2014 the FFmpeg
developers
built on Dec 7 2014 14:41:06 with gcc 4.9.1 (GCC)
configuration: --enable-gpl --enable-libx264 --disable-doc
--disable-htmlpages --disable-podpages --disable-ffserver
--disable-network --enable-libvpx
libavutil 54. 15.100 / 54. 15.100
libavcodec 56. 14.100 / 56. 14.100
libavformat 56. 15.102 / 56. 15.102
libavdevice 56. 3.100 / 56. 3.100
libavfilter 5. 2.103 / 5. 2.103
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20141107_test1-loses2frames.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf56.15.102
Duration: 00:00:22.08, start: 0.000000, bitrate: 7661 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
1280x720, 7149 kb/s, 29.91 fps, 30 tbr, 15360 tbn, 30720 tbc (default)
Metadata:
handler_name : DataHandler
Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 32000 Hz,
mono, s16, 512 kb/s (default)
Metadata:
handler_name : DataHandler
It thinks the frame rate should be 29.91 fps. So why does it correct
itself only at the joint?
Looking back in the output from when this file was created, it DOES say
it knew the output file should be 30.0 fps.
Loading #2 in avidemux shows one I frame every 10 seconds. If I ignore
the warped time stamp, All I-frames look correct. Note the length says
it is 21:21.13 and fps is 1.5
> ffmpeg -i 20141107_test2-freezes.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20141107_test2-freezes.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf56.15.102
Duration: 00:21:21.13, start: 0.000000, bitrate: 393 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
1280x720, 367 kb/s, 1.50 fps, 30 tbr, 15360 tbn, 30720 tbc (default)
Metadata:
handler_name : DataHandler
Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 32000 Hz,
mono, s16, 512 kb/s (default)
Metadata:
handler_name : DataHandler
Trying ffplay for playback, has same problem as mplayer, so can't blame
mplayer.
Loading #3 in avidemux shows each I-frame to be every 0.0282 seconds
> ffmpeg -i 20141107_test3-fails.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20141107_test3-fails.mov':
encoder : Lavf56.15.102
Duration: 00:00:54.00, start: 0.000000, bitrate: 7985 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
1280x720, 132398 kb/s, 531.60 fps, 30 tbr, 19200 tbn,
Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 32000 Hz,
mono, s16, 512 kb/s (default)
531 fps? but this time the duration correctly says 54 seconds. Is there
a memory leak? The fps and length are appearing more like random than a
pattern.
So how do I force it to write the output at 30 fps? If I add -r 30 , the
new console output now does show a change for tbc to 30
> ffmpeg -f concat -i concat-list3.txt -r 30 -c copy
20141107_test3-rate30.mov
Output #0, mov, to '20141107_test3-rate30.mov':
Metadata:
encoder : Lavf56.15.102
Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p, 1280x720,
q=2-31, 7453 kb/s, 30 fps, 15360 tbn, 30 tbc
Stream #0:1: Audio: pcm_s16le (sowt / 0x74776F73), 32000 Hz, mono,
512 kb/s
but playing the resulting file still has the problem, and using identify
also shows no effective change.
> ffmpeg -i 20141107_test3-rate30.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '20141107_test3-rate30.mov':
encoder : Lavf56.15.102
Duration: 00:00:54.00, start: 0.000000, bitrate: 7985 kb/s
Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
1280x720, 131538 kb/s, 528.15 fps, 30 tbr, 15360 tbn,
Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 32000 Hz,
mono, s16, 512 kb/s (default)
Now that I've narrowed down the problem further, this looks very similar
to another problem I started having last month when I started switching
my scripts over to the new ffmpeg, trying to take advantage of the
libx264 I now have installed..
I'll have to find the exact file and command line... but in brief
memory, I was resizing videos, and it would alter the fps from 30 to 60
fps, so that playback showed each frame twice when I pressed the frame
advance key. Adding -r 30 solved that problem.
Stewart
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