Hi,
I have encountered some DPX that has an fps of 18. It seems that ffmpeg skips
every few frames when decoding - at least when I performed a framemd5 analysis.
I noticed that 30522 frames were decoded, 10172 were dropped.
It seems that adding -framerate 18 to as an input option resolves the issue,
but should ffmpeg not auto-detect the FPS?
I can replicate the issue with just a few frames (I will see if I can share the
samples) - here's 17 frames decoded with nullm followed by the md5 muxer where
only 14 frames are processed.:
$ ./ffmpeg -i ffmpeg-1-01_%06d.dpx -f null -
ffmpeg version N-92683-g32601fb821 Copyright (c) 2000-2018 the FFmpeg developers
built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
configuration:
libavutil 56. 24.101 / 56. 24.101
libavcodec 58. 42.100 / 58. 42.100
libavformat 58. 24.100 / 58. 24.100
libavdevice 58. 6.101 / 58. 6.101
libavfilter 7. 46.101 / 7. 46.101
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
Input #0, image2, from 'ffmpeg-1-01_%06d.dpx':
Duration: 00:00:00.68, start: 0.000000, bitrate: N/A
Stream #0:0: Video: dpx, gbrp10le, 3840x2160, 18 tbr, 25 tbn, 18 tbc
Stream mapping:
Stream #0:0 -> #0:0 (dpx (native) -> wrapped_avframe (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
Metadata:
encoder : Lavf58.24.100
Stream #0:0: Video: wrapped_avframe, gbrp10le, 3840x2160, q=2-31, 200 kb/s,
18 fps, 18 tbn, 18 tbc
Metadata:
encoder : Lavc58.42.100 wrapped_avframe
[null @ 0x7f88d3000600] Application provided invalid, non monotonically
increasing dts to muxer in stream 0: 1 >= 1
[null @ 0x7f88d3000600] Application provided invalid, non monotonically
increasing dts to muxer in stream 0: 4 >= 4
[null @ 0x7f88d3000600] Application provided invalid, non monotonically
increasing dts to muxer in stream 0: 6 >= 6
[null @ 0x7f88d3000600] Application provided invalid, non monotonically
increasing dts to muxer in stream 0: 9 >= 9
frame= 17 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.72 bitrate=N/A speed= 1.1x
video:9kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing
overhead: unknown
$ ./ffmpeg -i ffmpeg-1-01_%06d.dpx -f md5 -
ffmpeg version N-92683-g32601fb821 Copyright (c) 2000-2018 the FFmpeg developers
built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
configuration:
libavutil 56. 24.101 / 56. 24.101
libavcodec 58. 42.100 / 58. 42.100
libavformat 58. 24.100 / 58. 24.100
libavdevice 58. 6.101 / 58. 6.101
libavfilter 7. 46.101 / 7. 46.101
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
Input #0, image2, from 'ffmpeg-1-01_%06d.dpx':
Duration: 00:00:00.68, start: 0.000000, bitrate: N/A
Stream #0:0: Video: dpx, gbrp10le, 3840x2160, 18 tbr, 25 tbn, 18 tbc
Stream mapping:
Stream #0:0 -> #0:0 (dpx (native) -> rawvideo (native))
Press [q] to stop, [?] for help
Output #0, md5, to 'pipe:':
Metadata:
encoder : Lavf58.24.100
Stream #0:0: Video: rawvideo (G3[0][10] / 0xA003347), gbrp10le, 3840x2160,
q=2-31, 4478976 kb/s, 18 fps, 18 tbn, 18 tbc
Metadata:
encoder : Lavc58.42.100 rawvideo
frame= 5 fps=0.0 q=-0.0 size= 0kB time=00:00:00.27 bitrate=
0.0kbits/frame= 9 fps=7.5 q=-0.0 size= 0kB time=00:00:00.50 bitrate=
0.0kbits/frame= 12 fps=7.0 q=-0.0 size= 0kB time=00:00:00.66 bitrate=
0.0kbits/MD5=123fb3ff58ca94c842453b518aeb6a9a
frame= 14 fps=6.6 q=-0.0 Lsize= 0kB time=00:00:00.77 bitrate=
0.4kbits/s dup=0 drop=3 speed=0.364x
video:680400kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
Best,
Kieran O'Leary
Irish Film Institute
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