[XviD-devel] testing process

Edouard Gomez ed.gomez at free.fr
Mon Oct 25 14:33:28 CEST 2004

Selon Tom Jacobs <T.R.Jacobs at lboro.ac.uk>:
> i have nearly finished by threading of xvid and am looking more closely at
> testing my code. i have numerous test sequences in qcif format. what is the
> best way to test my work? i think i would like to know the psnr of my
> modified code against the original image and an unmodified xvid so i can
> see how my modifications affect the over all performance of the codec. i
> can get the compressed mp4 back into qcif if that helps but i don't know
> what programme would be best to use to obtains some results

First of all, your modifications should not impact one thread coding, which
means that for a single thread encoder, the resulting bitstream should be 1:1
with non threaded encoder, eg: test it with md5sum.

For all threaded cases, you have two ways to test your code:
 - see how bigger streams are at constant quantizer (this measure the loss in
coding efficiency caused by the ME zones splitting)
 - see how much PSNR you lose at constant file size (2pass coding).

And depending on your code changes, maybe all multi threaded cases should behave
exactly the same, in that case test resulting streams with md5sum, if not then
just forget about this.

examples/xvid_encraw allows all that, PSNR tracking, framesize tracking etc...
just feed it with raw yuv streams and choose the right options for your tests.

xvid_encraw has the advantage to be a very thin layer upon xvidcore, so you're
sure nothing introduces bugs in between xvidcore and the demuxer. Once
xvid_encraw validate your changes, you can give a try at a normal test series
with your favorite encoding app.

Edouard Gomez

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