postproc − Re−sync or re−quantize an MPEG file


postproc is designed to do simple post−processing on MPEG video files, such as those generated by tovid. It can adjust audio/video sync, and re−quantize (shrink) without re−encoding.




−audiodelay NUM

Delay the audio stream by NUM milliseconds. Use this if your final output has audio that is not synced with the video. For example, if the audio comes 2 seconds sooner than the video, use "−audiodelay 2000". Use a negative number for audio that comes later than the video.


Analyze the audio stream and then normalize the volume of the audio. This is useful if the audio is too quiet or too loud, or you want to make volume consistent for a bunch of videos. Similar to running normalize without any parameters. The default is −12dB average level with 0dB gain.

−amplitude NUM[dB]

In addition to analyzing and normalizing, apply the gain to the audio such that the ’average’ (RMS) sound level is NUM. Valid values range 0.0 − 1.0, with 0.0 being silent and 1.0 being full scale. Use NUMdB for a decibel gain below full scale (the default without −amplitude is −12dB).

−shrink NUM

Shrink the video stream by a factor of NUM. May be a decimal value. A value of 1.0 means the video will be the same size; larger values cause more reduction in size. Beyond 2.0, the returns are diminishing.


Run all processes in parallel and pipe into multiplexer, should increase speed significantly.


Save output in a temporary file, for later viewing if something goes wrong.


idvid(1), makedvd(1), makemenu(1), makeslides(1), makevcd(1), makexml(1), postproc(1), tovid(1), todisc(1)


For further assistance, contact information, forum and IRC links, please refer to the tovid homepage (