[FFmpeg-trac] #1523(undetermined:new): automatic set a default -slices value for ffv1 version 3

[FFmpeg]

#1523: automatic set a default -slices value for ffv1 version 3
-------------------------------------+-------------------------------------
             Reporter:  dericed      |                     Type:
               Status:  new          |  enhancement
            Component:               |                 Priority:  normal
  undetermined                       |                  Version:  git-
             Keywords:               |  master
  ffv1,threads                       |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 If I encode to ffv1 version 3 without specifying a -slices value, then
 slices defaults to zero, which is not allowed, and thus the command fails.
 Because of this encoding with ffv1 version 3 does not seem to be possible
 without explicitly stating the slice count. I think most users may not be
 so picky about slice count and would accept a default value if they do not
 specify it. Can ffv1 version 3 default to a value for -slices based on
 detection number of (available) CPU cores.

 How to reproduce:
 {{{
 ffmpeg started on 2012-07-10 at 21:06:53
 Report written to "ffmpeg-20120710-210653.log"
 Command line:
 ffmpeg -report -y -f lavfi -t 1 -i testsrc -c:v ffv1 -strict experimental
 -level 3 out.mov
 ffmpeg version 0.11.1.git Copyright (c) 2000-2012 the FFmpeg developers
   built on Jul  3 2012 20:17:26 with gcc 4.2.1 (Apple Inc. build 5666)
 (dot 3)
   configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared
 --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables
 --enable-libfreetype --cc=/usr/bin/gcc-4.2 --enable-libx264 --enable-
 libfaac --enable-libmp3lame --enable-librtmp --enable-libtheora --enable-
 libvorbis --enable-libvpx --enable-libxvid --enable-libopencore-amrnb
 --enable-libopencore-amrwb --enable-libass --enable-libvo-aacenc --enable-
 libopenjpeg
   libavutil      51. 63.100 / 51. 63.100
   libavcodec     54. 32.100 / 54. 32.100
   libavformat    54. 14.100 / 54. 14.100
   libavdevice    54.  0.100 / 54.  0.100
   libavfilter     3.  0.101 /  3.  0.101
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0. 15.100 /  0. 15.100
   libpostproc    52.  0.100 / 52.  0.100
 [Parsed_testsrc_0 @ 0x7fef13418540] size:320x240 rate:25/1
 duration:-1.000000 sar:1/1
 [out @ 0x7fef13418a40] No opaque field provided
 [lavfi @ 0x7fef1384e200] All info found
 [lavfi @ 0x7fef1384e200] Estimating duration from bitrate, this may be
 inaccurate
 Input #0, lavfi, from 'testsrc':
   Duration: N/A, start: 0.000000, bitrate: N/A
     Stream #0:0, 1, 1/25: Video: rawvideo (RGB[24] / 0x18424752), rgb24,
 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
 -t is not an input option, keeping it for the next output; consider fixing
 your command line.
 [buffer @ 0x7fef13419c00] Setting entry with key 'video_size' to value
 '320x240'
 [buffer @ 0x7fef13419c00] Setting entry with key 'pix_fmt' to value '2'
 [buffer @ 0x7fef13419c00] Setting entry with key 'time_base' to value
 '1/25'
 [buffer @ 0x7fef13419c00] Setting entry with key 'pixel_aspect' to value
 '1/1'
 [buffer @ 0x7fef13419c00] Setting entry with key 'sws_param' to value
 'flags=2'
 [buffer @ 0x7fef13419c00] Setting entry with key 'frame_rate' to value
 '25/1'
 [graph 0 input from stream 0:0 @ 0x7fef13419ca0] w:320 h:240 pixfmt:rgb24
 tb:1/25 fr:25/1 sar:1/1 sws_param:flags=2
 [output stream 0:0 @ 0x7fef13419ec0] No opaque field provided
 [format @ 0x7fef1341a320] auto-inserting filter 'auto-inserted scaler 0'
 between the filter 'Parsed_null_0' and the filter 'format'
 [auto-inserted scaler 0 @ 0x7fef1341a680] w:320 h:240 fmt:rgb24 sar:1/1 ->
 w:320 h:240 fmt:bgr0 sar:1/1 flags:0x4
 [ffv1 @ 0x7fef13854400] detected 2 logical cores
 [ffv1 @ 0x7fef13854400] Unsupported number 0 of slices requested, please
 specify a supported number with -slices (ex:4,6,9,12,16, ...)
 Output #0, mov, to 'out.mov':
     Stream #0:0, 0, 1/90000: Video: ffv1, bgr0, 320x240 [SAR 1:1 DAR 4:3],
 q=2-31, 200 kb/s, 90k tbn, 25 tbc
 Stream mapping:
   Stream #0:0 -> #0:0 (rawvideo -> ffv1)
 Error while opening encoder for output stream #0:0 - maybe incorrect
 parameters such as bit_rate, rate, width or height
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1523>
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