Output of crop as rawvideo is offset by one frame

[Denis Warburton]

Summary of the bug:

I am using FFmpeg to extract a single line from every frame of a ProRes Quicktime file, which is then written to a file as raw, 8-bit grayscale values. (The output file is then read by programs which process waveforms for closed captioning and other data signals.)

The issue that I have encountered is that FFmpeg appears to skip the first frame of the input ProRes file (frame 0), resulting in a one-frame offset between the original file and the extracted data. In the provided sample, the closed caption waveform appears one frame early in the extracted data (in the position of frame 25, instead of 26). This is unexpected behavior, as I didn’t specify any offset or change in duration.

I am uncertain if this is a bug, or intended behavior that can be modified via an option. Either way, I greatly thank you in advance for your help and insight into this matter.

The sample file (6.8 MB) can be downloaded from the following URL:
<removed>

A timecode / frame count burn of the provided sample (created using DaVinci Resolve) can be found at this URL:
<removed>

[

The “line21” output can be visualized with imagemagick using the following command:

convert -size 720x60 -depth 8 gray:BTA003-05.line21 BTA003-05.jpg

The provided sample was extracted from the original ProRes file with ffmpeg v4.4 using the following command:

ffmpeg -ss 6 -i BTA003-05.mov -t 2 -map 0 -c copy ~/Desktop/Sample/BTA003-05.mov

]

How to reproduce:

ffmpeg started on 2022-04-04 at 17:24:32
Report written to "ffmpeg-20220404-172432.log"
Log level: 48
Command line:
/Users/useraccount/Downloads/ffmpeg -i /Users/useraccount/Desktop/Sample/BTA003-05.mov -filter:v "crop=720:1:0:1" -f rawvideo -vcodec rawvideo -pix_fmt gray8 /Users/useraccount/Desktop/Sample/BTA003-05.line21 -report
ffmpeg version N-106490-gbb4e0f6162-tessus Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.17)
  configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvmaf --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-version3 --pkg-config-flags=--static --disable-ffplay
  libavutil      57. 24.101 / 57. 24.101
  libavcodec     59. 25.100 / 59. 25.100
  libavformat    59. 20.101 / 59. 20.101
  libavdevice    59.  6.100 / 59.  6.100
  libavfilter     8. 30.100 /  8. 30.100
  libswscale      6.  6.100 /  6.  6.100
  libswresample   4.  6.100 /  4.  6.100
  libpostproc    56.  5.100 / 56.  5.100
Splitting the commandline.
Reading option '-i' ... matched as input url with argument '/Users/useraccount/Desktop/Sample/BTA003-05.mov'.
Reading option '-filter:v' ... matched as option 'filter' (set stream filtergraph) with argument 'crop=720:1:0:1'.
Reading option '-f' ... matched as option 'f' (force format) with argument 'rawvideo'.
Reading option '-vcodec' ... matched as option 'vcodec' (force video codec ('copy' to copy stream)) with argument 'rawvideo'.
Reading option '-pix_fmt' ... matched as option 'pix_fmt' (set pixel format) with argument 'gray8'.
Reading option '/Users/useraccount/Desktop/Sample/BTA003-05.line21' ... matched as output url.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input url /Users/useraccount/Desktop/Sample/BTA003-05.mov.
Successfully parsed a group of options.
Opening an input file: /Users/useraccount/Desktop/Sample/BTA003-05.mov.
[NULL @ 0x7fa44cd007c0] Opening '/Users/useraccount/Desktop/Sample/BTA003-05.mov' for reading
[file @ 0x7fa44cd00c80] Setting default whitelist 'file,crypto,data'
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] ISO: File Type Major Brand: qt  
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Unknown dref type 0x206c7275 size 12
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Processing st: 0, edit list 0 - media time: 328, duration: 24072
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] drop a frame at curr_cts: 0 @ 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Unknown dref type 0x206c7275 size 12
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Processing st: 1, edit list 0 - media time: 1919, duration: 96384
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] drop a frame at curr_cts: 0 @ 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] skip 895 audio samples from curr_cts: 1024
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] Before avformat_find_stream_info() pos: 6769759 bytes read:35499 seeks:1 nb_streams:2
[prores @ 0x7fa44cd015c0] Auto bitdepth precision. Use 10b decoding based on codec tag.
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] demuxer injecting skip 1919 / discard 0
[prores @ 0x7fa44cd015c0] Format yuv422p10le chosen by get_format().
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] All info found
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fa44cd007c0] After avformat_find_stream_info() pos: 8036 bytes read:68267 seeks:2 frames:2
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/useraccount/Desktop/Sample/BTA003-05.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf58.76.100
  Duration: 00:00:02.01, start: 0.000000, bitrate: 26957 kb/s
  Stream #0:0[0x1](eng), 1, 1/11988: Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, smpte170m/unknown/unknown, bottom coded first (swapped)), 720x486, 25785 kb/s, SAR 10:11 DAR 400:297, 29.97 fps, 29.97 tbr, 11988 tbn (default)
    Metadata:
      handler_name    : Apple Video Media Handler
      vendor_id       : FFMP
  Stream #0:1[0x2](eng), 1, 1/48000: Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Metadata:
      handler_name    : Apple Sound Media Handler
      vendor_id       : [0][0][0][0]
Successfully opened the file.
Parsing a group of options: output url /Users/useraccount/Desktop/Sample/BTA003-05.line21.
Applying option filter:v (set stream filtergraph) with argument crop=720:1:0:1.
Applying option f (force format) with argument rawvideo.
Applying option vcodec (force video codec ('copy' to copy stream)) with argument rawvideo.
Applying option pix_fmt (set pixel format) with argument gray8.
Successfully parsed a group of options.
Opening an output file: /Users/useraccount/Desktop/Sample/BTA003-05.line21.
[file @ 0x7fa44cd05f40] Setting default whitelist 'file,crypto,data'
Successfully opened the file.
detected 12 logical cores
[prores @ 0x7fa44cd06c80] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd07640] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd08040] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd08a00] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd093c0] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd09d80] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0a780] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0b140] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0bb00] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0c4c0] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0cec0] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0d880] Auto bitdepth precision. Use 10b decoding based on codec tag.
[prores @ 0x7fa44cd0e240] Auto bitdepth precision. Use 10b decoding based on codec tag.
Stream mapping:
  Stream #0:0 -> #0:0 (prores (native) -> rawvideo (native))
Press [q] to stop, [?] for help
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[prores @ 0x7fa44cd06c80] Format yuv422p10le chosen by get_format().
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[Parsed_crop_0 @ 0x7fa44e900040] Setting 'out_w' to value '720'
[Parsed_crop_0 @ 0x7fa44e900040] Setting 'out_h' to value '1'
[Parsed_crop_0 @ 0x7fa44e900040] Setting 'x' to value '0'
[Parsed_crop_0 @ 0x7fa44e900040] Setting 'y' to value '1'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] Setting 'video_size' to value '720x486'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] Setting 'pix_fmt' to value '64'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] Setting 'time_base' to value '1/11988'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] Setting 'pixel_aspect' to value '10/11'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] Setting 'frame_rate' to value '2997/100'
[graph 0 input from stream 0:0 @ 0x7fa44e900580] w:720 h:486 pixfmt:yuv422p10le tb:1/11988 fr:2997/100 sar:10/11
[format @ 0x7fa44e900a40] Setting 'pix_fmts' to value 'gray'
[auto_scale_0 @ 0x7fa44e901080] w:iw h:ih flags:'' interl:0
[format @ 0x7fa44e900a40] auto-inserting filter 'auto_scale_0' between the filter 'Parsed_crop_0' and the filter 'format'
[AVFilterGraph @ 0x7fa44ce00e00] query_formats: 4 queried, 3 merged, 1 already done, 0 delayed
[Parsed_crop_0 @ 0x7fa44e900040] w:720 h:486 sar:10/11 -> w:720 h:1 sar:10/11
[auto_scale_0 @ 0x7fa44e901080] w:720 h:1 fmt:yuv422p10le sar:10/11 -> w:720 h:1 fmt:gray sar:10/11 flags:0x0
[auto_scale_0 @ 0x7fa44e901080] w:720 h:1 fmt:yuv422p10le sar:10/11 -> w:720 h:1 fmt:gray sar:10/11 flags:0x0
[auto_scale_0 @ 0x7fa44e901080] w:720 h:1 fmt:yuv422p10le sar:10/11 -> w:720 h:1 fmt:gray sar:10/11 flags:0x0
[auto_scale_0 @ 0x7fa44e901080] w:720 h:1 fmt:yuv422p10le sar:10/11 -> w:720 h:1 fmt:gray sar:10/11 flags:0x0
Output #0, rawvideo, to '/Users/useraccount/Desktop/Sample/BTA003-05.line21':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf59.20.101
  Stream #0:0(eng), 0, 100/2997: Video: rawvideo (Y800 / 0x30303859), gray(pc, smpte170m/unknown/unknown, progressive), 720x1 [SAR 10:11 DAR 7200:11], q=2-31, 172 kb/s, 29.97 fps, 29.97 tbn (default)
    Metadata:
      handler_name    : Apple Video Media Handler
      vendor_id       : FFMP
      encoder         : Lavc59.25.100 rawvideo
Clipping frame in rate conversion by 0.000008
frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
[out_0_0 @ 0x7fa44e9008c0] EOF on sink link out_0_0:default.
No more output streams to write to, finishing.
frame=   60 fps=0.0 q=-0.0 Lsize=      42kB time=00:00:02.00 bitrate= 172.6kbits/s speed=48.8x    
video:42kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
Input file #0 (/Users/useraccount/Desktop/Sample/BTA003-05.mov):
  Input stream #0:0 (video): 61 packets read (6472080 bytes); 60 frames decoded; 
  Input stream #0:1 (audio): 1 packets read (3072 bytes); 
  Total: 62 packets (6475152 bytes) demuxed
Output file #0 (/Users/useraccount/Desktop/Sample/BTA003-05.line21):
  Output stream #0:0 (video): 60 frames encoded; 60 packets muxed (43200 bytes); 
  Total: 60 packets (43200 bytes) muxed
[AVIOContext @ 0x7fa44cd06000] Statistics: 43200 bytes written, 0 seeks, 1 writeouts
60 frames successfully decoded, 0 decoding errors
[AVIOContext @ 0x7fa44cd00e00] Statistics: 6799419 bytes read, 2 seeks

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.

[Elon Musk]

-ignore_editlist 1

[Denis Warburton]

Confirmed: adding -ignore_editlist 1 before the -i parameter solved the issue. Thank you!

(Example files have been deleted.)

Replying to Elon Musk:

-ignore_editlist 1