Comments on: How to set target file sizes in ffmpeg http://www.helyar.net/2009/how-to-set-target-file-sizes-in-ffmpeg/ From the desktop of George Helyar Sat, 04 Feb 2012 18:35:32 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Joe1 http://www.helyar.net/2009/how-to-set-target-file-sizes-in-ffmpeg/comment-page-1/#comment-790 Joe1 Mon, 26 Jul 2010 22:19:46 +0000 http://www.helyar.net/?p=240#comment-790 George, you are my hero! I'm testing your script now in re-encoding a 1.4 GB big avi to a more manageable 700MB file size. Thanks for posting this! George, you are my hero! I’m testing your script now in re-encoding a 1.4 GB big avi to a more manageable 700MB file size. Thanks for posting this!

]]> By: George Helyar http://www.helyar.net/2009/how-to-set-target-file-sizes-in-ffmpeg/comment-page-1/#comment-18 George Helyar Sun, 28 Jun 2009 00:03:08 +0000 http://www.helyar.net/?p=240#comment-18 ffmpeg is the basis of pretty much every other video encoding software (including mencoder) on both Windows and Linux. Often, these allow you to set the target size in their GUIs but there is nothing actually built into ffmpeg to let you do it. When batch encoding hundreds of files, it is good to be able to do it from the command line and with no effort :) <a href="http://lame.sourceforge.net/" rel="nofollow">LAME</a> is still available for free but probably subject to licensing like not using it commercially. ffmpeg can be simple enough to encode the audio from a DVD as such: <code>ffmpeg -i mydvd.vob mydvd.mp3</code> and will use the lame mp3 encoder to do it (assuming it is available). Bitrates etc should probably be set though, the default is 64k and will sound pretty bad. The free audio encoder I am using here is <a href="http://www.audiocoding.com/" rel="nofollow">faac</a> (free aac). The paired decoder is faad (coder + decoder = codec in the same way that modem = modulator + demodulator). This will obviously work in an mp4 container for output but I don't know about anything else. ".aac" is raw aac but I think without the headers you will not be able to play it. I don't know if it works with virtualdub. DVD and Blu-ray both seem to use ac3. For video, H.264 blows divx and xvid completely out of the water. H.264 is an implementation of MPEG-4 video (as used on HDDVD and Blu-ray). x264 is a free implementation of H.264 made by the same people as VLC. ffmpeg is the basis of pretty much every other video encoding software (including mencoder) on both Windows and Linux. Often, these allow you to set the target size in their GUIs but there is nothing actually built into ffmpeg to let you do it.

When batch encoding hundreds of files, it is good to be able to do it from the command line and with no effort :)

LAME is still available for free but probably subject to licensing like not using it commercially. ffmpeg can be simple enough to encode the audio from a DVD as such:
ffmpeg -i mydvd.vob mydvd.mp3 and will use the lame mp3 encoder to do it (assuming it is available). Bitrates etc should probably be set though, the default is 64k and will sound pretty bad.

The free audio encoder I am using here is faac (free aac). The paired decoder is faad (coder + decoder = codec in the same way that modem = modulator + demodulator). This will obviously work in an mp4 container for output but I don’t know about anything else. “.aac” is raw aac but I think without the headers you will not be able to play it. I don’t know if it works with virtualdub.

DVD and Blu-ray both seem to use ac3.

For video, H.264 blows divx and xvid completely out of the water. H.264 is an implementation of MPEG-4 video (as used on HDDVD and Blu-ray). x264 is a free implementation of H.264 made by the same people as VLC.

]]> By: Matt http://www.helyar.net/2009/how-to-set-target-file-sizes-in-ffmpeg/comment-page-1/#comment-16 Matt Sat, 27 Jun 2009 13:43:21 +0000 http://www.helyar.net/?p=240#comment-16 I don't know about linux, but in windows you can more or less set the file size in virtual dub, which is what i assume people do when they rip things to pirate them. Having installed DivX or Xvid codec, you can go Video > compression (Ctrl+P). Select DivX and press configure and you can click on the little calculator (in DivX 6.5, I'm updating to 7.0 as i type this so it might be different already) and you can set a size or chose a preset, which includes "700MB (CD-R)" and it will estimate the bitrate to use to get that file size. The process is similar for Xvid. Depending on the input format and the codecs you have installed, you can either recompress the audio from audio > full stream processing audio > compression or just leave it as the source file with audio > direct stream copy. When Lame MP3 codec was freely available I always recompressed, now I can't find a single decent, free audio codec that works with virtualdub. I don’t know about linux, but in windows you can more or less set the file size in virtual dub, which is what i assume people do when they rip things to pirate them.

Having installed DivX or Xvid codec, you can go
Video > compression (Ctrl+P).

Select DivX and press configure and you can click on the little calculator (in DivX 6.5, I’m updating to 7.0 as i type this so it might be different already) and you can set a size or chose a preset, which includes “700MB (CD-R)” and it will estimate the bitrate to use to get that file size. The process is similar for Xvid.

Depending on the input format and the codecs you have installed, you can either recompress the audio from
audio > full stream processing
audio > compression

or just leave it as the source file with
audio > direct stream copy.

When Lame MP3 codec was freely available I always recompressed, now I can’t find a single decent, free audio codec that works with virtualdub.

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