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Editorial Team
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Asked: 2026-05-26T19:32:40+00:00

I convert AVI to FLV with ffmpeg using -sameq parameter (same quality): ffmpeg -i

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I convert AVI to FLV with ffmpeg using -sameq parameter (same quality):

ffmpeg -i test.avi -sameq -f flv sameq.flv

The resulting file has the same video and audio quality as the original, but it’s more than twice the original file size:

84M sameq.flv
41M test.avi

Why does it happen?

Transcoder output:

ffmpeg version N-34750-g070d2d7, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov 12 2011 11:23:07 with gcc 4.6.1
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-x11grab
  libavutil    51. 24. 1 / 51. 24. 1
  libavcodec   53. 33. 0 / 53. 33. 0
  libavformat  53. 20. 0 / 53. 20. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 48. 0 /  2. 48. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
Input #0, avi, from 'test.avi':
  Duration: 00:06:30.00, start: 0.000000, bitrate: 866 kb/s
    Stream #0:0: Video: mpeg4 (Advanced Real Time Simple Profile) (DIVX / 0x58564944), yuv420p, 400x300 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, mono, s16, 64 kb/s
[buffer @ 0xa247ae0] w:400 h:300 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
Output #0, flv, to 'sameq.flv':
  Metadata:
    encoder         : Lavf53.20.0
    Stream #0:0: Video: flv1 ([2][0][0][0] / 0x0002), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 1k tbn, 25 tbc
    Stream #0:1: Audio: mp3 ([2][0][0][0] / 0x0002), 44100 Hz, mono, s16, 128 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg4 -> flv)
  Stream #0:1 -> #0:1 (mp3 -> libmp3lame)
Press [q] to stop, [?] for help
frame= 9742 fps=255 q=0.0 Lsize=   85074kB time=00:06:30.00 bitrate=1787.0kbits/s    
video:79163kB audio:5525kB global headers:0kB muxing overhead 0.455568%
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1 Answer

  1. Editorial Team

    Two thing comes to mind:

    1. Compress a video without audio stream to eliminate the audio portion of this issue. BTW, the audio source is HALF the bitrate of the output, that increases the size a little. Use -ar and -ab switches to control the output.

    2. Check out this article on qscale vs quality using -qscale option. Add in the -b (bitrate) and -s (size) and tweak it to your needs.

    When all fails, there are a few switches you can try from the ffmpeg website or try using the new H.264 compression, the two pass option is recommended. Have fun compressing

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