Phil's Blog

Hi all !

Today I spent quite 2 hours to test and compare the theora alpha7 video codec. So I used ffmpeg2theora. I want to know if the theora quality is better than x264 at the same bitrate. Today, at around 480kb/s the answer is no.


Here are some results. The original video is a spiderman 3 trailer from AlloCine.fr. The main caracteristics are :

- Duration: 00:02:37.6, start: 0.000000,

- bitrate: 1029 kb/s,

- Stream #0.0: Video: mpeg4, yuv420p, 480x272, 25.00 fps(r),

- Stream #0.1: Audio: mp3, 44100 Hz, stereo, 192 kb/s.


I used this command line to convert the video stream :

ffmpeg2theora -v QUALITY -S 0 --nosound -o trailer.out Spider_Man_3_18726051_fa2_pod_xvid480.avi 

with QUALITY the quality from 1 to 10.

I used this one too :

ffmpeg2theora -V BITRATE -S 0 --nosound -o trailer.out Spider_Man_3_18726051_fa2_pod_xvid480.avi 

with BITRATE the bitrate in kb/s.

I try the --optimize option, which save 5% of the final size, but you need something like 2,2 times than the traditional methode to save only 5%!

Here are the results on a celeron 1GHz, 512 Mo Ram :

Comparison of various theora v1.0 alpha 7 codec

	Test 1	Test 2	Test 3	Test 4	Test 5	Test 6	Test 7
Sharpness	S0	S0	S0	S0	S0	S0	S0
Sound?	nosound	nosound	nosound	nosound	nosound	nosound	nosound
Birate (kb/s)/Quality	Birate 480	Birate 480	Quality 3 (~430kb/s)	Quality 4 (~500kb/s)	Quality 3.5	Quality 3.5	Quality 3.3 (~480kb/s)
--optimize?	yes	no	no	no	no	yes	no
Final Size	8,9 Mo	8,9 Mo	8,4 Mo	11 Mo	9,5 Mo	9,3 Mo	9,2 Mo
Time to encode	4min31	1min39	1min38	1min40	1min39	4min10	1min37

Ok, on this test there are no picture, neither video to watch. But trust me, x264 at same resolution, 2-pass encoding and an average bitrate of 480kb/s the quality is really better. It may be because there are really much options to choose.