[FFmpeg-user] Converted file size is bigger than source.

Anil Jangam anil_jangam at persistent.co.in
Fri May 13 20:48:25 CEST 2011

Inline comments.

> -----Original Message-----
> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
> bounces at ffmpeg.org] On Behalf Of Reindl Harald
> Sent: Friday, May 13, 2011 8:33 PM
> To: ffmpeg-user at ffmpeg.org
> Subject: Re: [FFmpeg-user] Converted file size is bigger than source.
> Am 13.05.2011 16:35, schrieb Anil Jangam:
> > Team,
> >
> > We have observed a scenario in which the size of the output
> transcoded file (~500kb) is greater than the size of the original video
> file (~140kb). Upon checking with media info tool (and with ffmpeg), we
> found that the video codec is h263 and audio codec used is amr (see
> below).
> >
> > Duration: 00:00:13.20, start: 0.000000, bitrate: 86 kb/s Stream
> > #0.0(und): Video: h263, yuv420p, 176x144 [PAR 12:11 DAR 4:3], 29.97
> > tbr, 30k tbn, 29.97 tbc Stream #0.1(und): Audio: libopencore_amrnb,
> > 8000 Hz, mono, s16
> >
> > Upon checking the properties of the output file, it shows that video
> codec is 'mpeg4_sp' and audio codec is 'aac_lc'.
> >
> > I am not sure if 'mpeg4_sp' is a low compression ratio codec as
> compare to the 'h263'. In that case, conversion of 'h263' coded video
> into 'mpeg4_sp' codec video will obviously result in the higher size of
> the transcoded output.
> >
> > Can you please confirm this?
> Depends on codec and bitrates
> 86 kb/s input file is a very low bitrate if your output is higher there
> is no other option as getting bigger with H264/AAC-Audio and a low
> bitrate it should get even smaller
> but anyways: post your full cli-call, without it is impossible to say
> anything away from guessing

[[Anil Jangam]] Thanks Reindl. The command line that we used is below.

ffmpeg -i video_dc.3gp -y -vcodec mpeg4 -acodec libfaac -ar 16000 -ab 96000 -async 1 out-video.3gp

What could be wrong in this case? What should we change here to keep the size of output video in control?


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