FFMPEG Same Quality Command Line

[Johnbil]

Need some advice on creating an FFMPEG command line to do 'Same Quality' video conversions.

It would need these options:
1) convert from MP4 to Xvid (using 2 passes)
2) resetting the resolution to 720x404
3) use MP3 audio with a 128 bitrate
4) resulting video should have the same quailty (bit rate) as the original

I have tried using some FFMPEG based VC converters, but in some cases, I haven't been able to achieve the same quality. I would like to try a command line instead.

Any help would be appreciated.

Regards...John B

[poisondeathray]

4) resulting video should have the same quailty (bit rate) as the original

Not possible with lossy codecs like xvid

You'd need higher bitrates (thus larger filesizes) for simliar quality as the original if you're were not resizing

This is especially true if your MP4 used more advanced compression like AVC. Going from AVC to xvid is worse than the other way around (you're going from better compression to worse compression)

-sameq in ffmpeg actually means "same quantizer" as the input file, which is not the same thing as "same quality"

[Johnbil]

Thanks for the really fast reply. Dumb question, would that apply to all AVI codecs? I usually watch these videos on TV via a DivX compatible DVD player.

[poisondeathray]

Thanks for the really fast reply. Dumb question, would that apply to all AVI codecs? I usually watch these videos on TV via a DivX compatible DVD player.

No, there are "lossless" codecs that are AVI compatible. e.g lagarith, ut video codec, huffyuv, many others . These won't work on your DivX DVD Player

All lossless codecs are much larger in filesize because the "lossless" nature refers to the uncompressed state, or decoded data from the original video (so they are smaller than the uncompressed size, but not the original compressed video)

The best you can do for that player - quality wise - is use a low quantizer e.g. q=2 , but the filesize will be large . Sometimes it may stutter unless you use an encoding profile compatible for DivX standalones (the encoding profile e.g. DivX or XviD home theatre profile "caps" bitrate peaks, which may cause stuttering on standalone units, but this potentially reduces quality as well)

[Johnbil]

OK. Thanks again.