Warning: data is not aligned! This can lead to a speedloss

[viric]

Summary of the bug:

How to reproduce:

% ffmpeg -ss 01:05:30 -i album-familiar-1.mkv -t 00:07:28 -vf "yadif, crop=690:560:16" -vcodec mpeg4 -vtag xvid  -qscale:v 4 -ac 1 -acodec libmp3lame -qscale:a 3 /tmp/tieta2.avi
ffmpeg version 1.1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 13 2013 22:22:02 with gcc 4.6.3 (GCC)
  configuration: --disable-static --prefix=/nix/store/1pja3gxi62f2hjwyww67ys84mxqfjgwm-ffmpeg-1.1 --enable-gpl --enable-postproc --enable-swscale --disable-ffplay --enable-shared --enable-runtime-cpudetect --enable-libmp3lame --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-vdpau
  libavutil      52. 13.100 / 52. 13.100
  libavcodec     54. 86.100 / 54. 86.100
  libavformat    54. 59.106 / 54. 59.106
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 32.100 /  3. 32.100
  libswscale      2.  1.103 /  2.  1.103
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, matroska,webm, from 'album-familiar-1.mkv':
  Metadata:
    ENCODER         : Lavf54.59.106
  Duration: 03:04:49.44, start: 0.000000, bitrate: 65334 kb/s
    Stream #0:0: Video: h264 (High 4:4:4 Predictive), yuv422p, 720x576, SAR 1:1 DAR 5:4, 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
    Stream #0:1: Audio: flac, 44100 Hz, stereo, s16 (default)
Output #0, avi, to '/tmp/tieta2.avi':
  Metadata:
    ISFT            : Lavf54.59.106
    Stream #0:0: Video: mpeg4 (xvid / 0x64697678), yuv420p, 690x560 [SAR 1:1 DAR 69:56], q=2-31, 200 kb/s, 25 tbn, 25 tbc (default)
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, mono, s16p (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mpeg4)
  Stream #0:1 -> #0:1 (flac -> libmp3lame)
Press [q] to stop, [?] for help
[swscaler @ 0x752040] Warning: data is not aligned! This can lead to a speedloss
frame=    6 fps=0.0 q=4.0 Lsize=      91kB time=00:00:00.24 bitrate=3118.7kbits/s dup=0 drop=7    
video:75kB audio:6kB subtitle:0 global headers:0kB muxing overhead 12.867035%

[viric]

The full log:

$ ffmpeg -v 9 -loglevel 99 -ss 00:24:50 -i album-familiar-2.mkv -t 00:00:30 -vf "yadif, crop=700:560:20" -vcodec mpeg4 -vtag xvid -qscale:v 4 -ac 1 -acodec libmp3lame -qscale:a 3 /tmp/calaguapa.avi 
ffmpeg version 1.1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 13 2013 22:22:02 with gcc 4.6.3 (GCC)
  configuration: --disable-static --prefix=/nix/store/1pja3gxi62f2hjwyww67ys84mxqfjgwm-ffmpeg-1.1 --enable-gpl --enable-postproc --enable-swscale --disable-ffplay --enable-shared --enable-runtime-cpudetect --enable-libmp3lame --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-vdpau
  libavutil      52. 13.100 / 52. 13.100
  libavcodec     54. 86.100 / 54. 86.100
  libavformat    54. 59.106 / 54. 59.106
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 32.100 /  3. 32.100
  libswscale      2.  1.103 /  2.  1.103
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set libav* logging level) with argument '9'.
Reading option '-loglevel' ... matched as option 'loglevel' (set libav* logging level) with argument '99'.
Reading option '-ss' ... matched as option 'ss' (set the start time offset) with argument '00:24:50'.
Reading option '-i' ... matched as input file with argument 'album-familiar-2.mkv'.
Reading option '-t' ... matched as option 't' (record or transcode "duration" seconds of audio/video) with argument '00:00:30'.
Reading option '-vf' ... matched as option 'vf' (video filters) with argument 'yadif, crop=700:560:20'.
Reading option '-vcodec' ... matched as option 'vcodec' (force video codec ('copy' to copy stream)) with argument 'mpeg4'.
Reading option '-vtag' ... matched as option 'vtag' (force video tag/fourcc) with argument 'xvid'.
Reading option '-qscale:v' ... matched as option 'qscale' (use fixed quality scale (VBR)) with argument '4'.
Reading option '-ac' ... matched as option 'ac' (set number of audio channels) with argument '1'.
Reading option '-acodec' ... matched as option 'acodec' (force audio codec ('copy' to copy stream)) with argument 'libmp3lame'.
Reading option '-qscale:a' ... matched as option 'qscale' (use fixed quality scale (VBR)) with argument '3'.
Reading option '/tmp/calaguapa.avi' ... matched as output file.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set libav* logging level) with argument 9.
Successfully parsed a group of options.
Parsing a group of options: input file album-familiar-2.mkv.
Applying option ss (set the start time offset) with argument 00:24:50.
Successfully parsed a group of options.
Opening an input file: album-familiar-2.mkv.
[matroska,webm @ 0x99f7e0] Format matroska,webm probed with size=2048 and score=100
st:0 removing common factor 1000000 from timebase
st:1 removing common factor 1000000 from timebase
[matroska,webm @ 0x99f7e0] File position before avformat_find_stream_info() is 669
[h264 @ 0x9a67e0] Using externally provided dimensions
[matroska,webm @ 0x99f7e0] All info found
[matroska,webm @ 0x99f7e0] File position after avformat_find_stream_info() is 1671349
Input #0, matroska,webm, from 'album-familiar-2.mkv':
  Metadata:
    ENCODER         : Lavf54.59.106
  Duration: 03:40:46.48, start: 0.000000, bitrate: 61847 kb/s
    Stream #0:0, 8, 1/1000: Video: h264 (High 4:4:4 Predictive), yuv422p, 720x576, 1/50, SAR 1:1 DAR 5:4, 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
    Stream #0:1, 3, 1/1000: Audio: flac, 44100 Hz, mono, s16 (default)
Successfully openened the file.
Parsing a group of options: output file /tmp/calaguapa.avi.
Applying option t (record or transcode "duration" seconds of audio/video) with argument 00:00:30.
Applying option vf (video filters) with argument yadif, crop=700:560:20.
Applying option vcodec (force video codec ('copy' to copy stream)) with argument mpeg4.
Applying option vtag (force video tag/fourcc) with argument xvid.
Applying option qscale:v (use fixed quality scale (VBR)) with argument 4.
Applying option ac (set number of audio channels) with argument 1.
Applying option acodec (force audio codec ('copy' to copy stream)) with argument libmp3lame.
Applying option qscale:a (use fixed quality scale (VBR)) with argument 3.
Successfully parsed a group of options.
Opening an output file: /tmp/calaguapa.avi.
y
Successfully openened the file.
[Parsed_yadif_0 @ 0x1b8f0a0] mode:0 parity:-1 deint:0
[crop @ 0x1b8f760] Setting 'w' to value '700'
[crop @ 0x1b8f760] Setting 'h' to value '560'
[crop @ 0x1b8f760] Setting 'x' to value '20'
[buffer @ 0x1b8d3c0] Setting entry with key 'video_size' to value '720x576'
[buffer @ 0x1b8d3c0] Setting entry with key 'pix_fmt' to value '4'
[buffer @ 0x1b8d3c0] Setting entry with key 'time_base' to value '1/1000'
[buffer @ 0x1b8d3c0] Setting entry with key 'pixel_aspect' to value '1/1'
[buffer @ 0x1b8d3c0] Setting entry with key 'sws_param' to value 'flags=2'
[buffer @ 0x1b8d3c0] Setting entry with key 'frame_rate' to value '25/1'
[graph 0 input from stream 0:0 @ 0x1b8d100] w:720 h:576 pixfmt:yuv422p tb:1/1000 fr:25/1 sar:1/1 sws_param:flags=2
[scale @ 0x1810260] Setting 'w' to value '0'
[scale @ 0x1810260] Setting 'h' to value '0'
[scale @ 0x1810260] Setting 'flags' to value '0x4'
[auto-inserted scaler 0 @ 0x1b90160] w:0 h:0 flags:'0x4' interl:0
[format @ 0x1b8fe20] auto-inserting filter 'auto-inserted scaler 0' between the filter 'Parsed_crop_1' and the filter 'format'
[Parsed_crop_1 @ 0x1b8f640] w:720 h:576 sar:1/1 -> w:700 h:560 sar:1/1
[auto-inserted scaler 0 @ 0x1b90160] w:700 h:560 fmt:yuv422p sar:1/1 -> w:700 h:560 fmt:yuv420p sar:1/1 flags:0x4
[abuffer @ 0x1c0b300] Setting entry with key 'time_base' to value '1/44100'
[abuffer @ 0x1c0b300] Setting entry with key 'sample_rate' to value '44100'
[abuffer @ 0x1c0b300] Setting entry with key 'sample_fmt' to value 's16'
[abuffer @ 0x1c0b300] Setting entry with key 'channel_layout' to value '0x4'
[graph 1 input from stream 0:1 @ 0x1810aa0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x4
[aformat @ 0x1c09420] Setting entry with key 'sample_fmts' to value 's32p,fltp,s16p'
[aformat @ 0x1c09420] Setting entry with key 'sample_rates' to value '44100,48000,32000,22050,24000,16000,11025,12000,8000'
[aformat @ 0x1c09420] Setting entry with key 'channel_layouts' to value '0x4'
[audio format for output stream 0:1 @ 0x1c09160] auto-inserting filter 'auto-inserted resampler 0' between the filter 'Parsed_anull_0' and the filter 'audio format for output stream 0:1'
[auto-inserted resampler 0 @ 0x1c12960] chl:mono fmt:s16 r:44100Hz -> chl:mono fmt:s16p r:44100Hz
[mpeg4 @ 0x1b8dd20] detected 1 logical cores
[mpeg4 @ 0x1b8dd20] intra_quant_bias = 0 inter_quant_bias = -64
[h264 @ 0x18197e0] detected 1 logical cores
Output #0, avi, to '/tmp/calaguapa.avi':
  Metadata:
    ISFT            : Lavf54.59.106
    Stream #0:0, 0, 1/25: Video: mpeg4 (xvid / 0x64697678), yuv420p, 700x560 [SAR 1:1 DAR 5:4], 1/25, q=2-31, 200 kb/s, 25 tbn, 25 tbc (default)
    Stream #0:1, 0, 32/1225: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, mono, s16p (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> mpeg4)
  Stream #0:1 -> #0:1 (flac -> libmp3lame)
Press [q] to stop, [?] for help
[h264 @ 0x18197e0] Using externally provided dimensions
[swscaler @ 0x17fe2e0] Warning: data is not aligned! This can lead to a speedloss
*** drop!
    Last message repeated 14 times
*** drop! 0 fps=0.0 q=0.0 size=      10kB time=00:00:00.00 bitrate=N/A dup=0 drop=15    
    Last message repeated 15 times
*** drop! 0 fps=0.0 q=0.0 size=      10kB time=00:00:00.00 bitrate=N/A dup=0 drop=31    
    Last message repeated 14 times
*** drop! 0 fps=0.0 q=0.0 size=      10kB time=00:00:00.00 bitrate=N/A dup=0 drop=46    
    Last message repeated 14 times
*** drop! 0 fps=0.0 q=0.0 size=      10kB time=00:00:00.00 bitrate=N/A dup=0 drop=61    
    Last message repeated 13 times
*** drop! 0 fps=0.0 q=0.0 size=      10kB time=00:00:00.00 bitrate=N/A dup=0 drop=75    
    Last message repeated 7 times
[libmp3lame @ 0x1b8e5a0] Trying to remove 47 more samples than there are in the queue
frame=    0 fps=0.0 q=0.0 Lsize=      48kB time=00:00:00.00 bitrate=N/A dup=0 drop=83    
video:0kB audio:35kB subtitle:0 global headers:0kB muxing overhead 36.491072%
Statistics: 25419425 bytes read, 3 seeks

[viric]

I added the ticket because I was told through irc that this line should not appear, and asked me to submit a ticket. But as time went by, someone told me it's normal. So it may be closed freely, as you want.

[Niklas Haas]

I'm pretty sure this is an unavoidable consequence of cropping to an unaligned offset. There is nothing we can do about this except do a full memcpy into an aligned buffer, which I'm pretty sure will not help.

swscale.c prints this message whenever the data pointers are not a multiple of 16, and since the yuv422p chroma plane is subsampled by a factor of 2 (in the horizontal direction), that means the chroma plane now starts at an offset of 8 (relative to the aligned image start).

Closing since everything is "working as intended". The message is just letting you know that you are requesting a crop that will inevitably slow down scaling.