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• What is the difference between "png" and "jpg -q 0" ?

  28 août 2015, par xkfz007

  When you are using ffmpeg to extract images from videos, what is the difference between "png" and "jpg -q 0" ?
  In my opinion, "-q 0" means the quantization is 0 and there is no compression. And the fact is the "jpg -q 0" is much smaller than "png"
  The commands like :

  ffmpeg -i a.mp4 image-%d.png
  
  ffmpeg -i a.mp4 -q 0 image-%d.jpg

• Revision 911e96a4eb : Revert "Revert "VP8 for ARMv8 by using NEON intrinsics 06" This reverts commit 8

  20 août 2014, par Johann

  Changed Paths :
   Delete /vp8/common/arm/neon/idct_dequant_0_2x_neon.asm

  
   Add /vp8/common/arm/neon/idct_dequant_0_2x_neon.c

  
   Delete /vp8/common/arm/neon/idct_dequant_full_2x_neon.asm

  
   Add /vp8/common/arm/neon/idct_dequant_full_2x_neon.c

  
   Modify /vp8/common/rtcd_defs.pl

  
   Modify /vp8/vp8_common.mk

  
  
  Revert "Revert "VP8 for ARMv8 by using NEON intrinsics 06" This reverts commit
  81ad047ee57ecb0e2c1ee4dcebda54a44ea54ae9. Revert "VP8 for ARMv8 by using NEON
  intrinsics 15" This reverts commit 727af7cebe3698b8493ba6c1360b0a6606c310fb."

  This reverts commit 920f803f2e2f41395311f96fec1b4a0c1b2b631a

  Change-Id : I410d9036214a1b18427cca70b4bc6d8239740737

• What is causing "unspecified pixel format" and "Error opening filters !" error in ffmpeg ?

  19 février 2019, par SJAndersonLA

  I’m writing an mp4 to HLS transcoding process that works as intended on files smaller than 7 gigabytes (sample size is 100 videos). When attempting to transcode anything larger than 7GB, it crashes.

  The command :

  ffmpeg 
  
    -i large_file.mp4 -y 
  
    -vf scale=w=1920:h=1080:force_original_aspect_ratio=decrease 
  
    -c:a aac 
  
    -ar 48000 
  
    -c:v h264 
  
    -profile:v main 
  
    -crf 20 
  
    -sc_threshold 0 
  
    -g 48 
  
    -keyint_min 48 
  
    -hls_time 4 
  
    -hls_playlist_type vod 
  
    -b:v 5000k 
  
    -maxrate 5350k 
  
    -bufsize 7500k 
  
    -b:a 192k 
  
    -hls_segment_filename /1080p_%03d.ts 
  
    -threads 0 
  
    /tmp/output-ef42dc65-1d3d-4682-b32b-68d7c712fb9c-raw-test/1080p.m3u8

  The error :

  ffmpeg version 3.2.12-1\x7edeb9u1 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  
    configuration: --prefix=/usr --extra-version='1~deb9u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libebur128 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
    libavutil      55. 34.101 / 55. 34.101
  
    libavcodec     57. 64.101 / 57. 64.101
  
    libavformat    57. 56.101 / 57. 56.101
  
    libavdevice    57.  1.100 / 57.  1.100
  
    libavfilter     6. 65.100 /  6. 65.100
  
    libavresample   3.  1.  0 /  3.  1.  0
  
    libswscale      4.  2.100 /  4.  2.100
  
    libswresample   2.  3.100 /  2.  3.100
  
    libpostproc    54.  1.100 / 54.  1.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x555888d821c0] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1280x720, 3856 kb/s): unspecified pixel format
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'large_file.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.26.101
  
    Duration: 05:56:12.51, start: 0.000000, bitrate: 4061 kb/s
  
      Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 1280x720, 3856 kb/s, 29.99 fps, 30 tbr, 100k tbn, 200k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 194 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  [buffer @ 0x555888d88180] Unable to parse option value "-1" as pixel format
  
      Last message repeated 1 times
  
  [buffer @ 0x555888d88180] Error setting option pix_fmt to value -1.
  
  [graph 0 input from stream 0:0 @ 0x555888d81e40] Error applying options to the filter.
  
  Error opening filters!

  The error says to try increasing analyzeduration and probesize, which I set to max value (based on an answer from this post), however that didn’t seem to change the behavior. I also suspected that the file was corrupted, but the fact that this is failing for all files larger than 7GB makes it more difficult to suggest its something not related to the size of the mp4.