Mnl
28th March 2004, 09:41
Recently I have been doing some tests of the video quality produced by AutoGK with Divx and Xvid respectively, and I must say that AutoGK does a very good job with both codecs. There's one thing I don't understand though: It seems to me that the compressibility percentage almost always is higher for xvid, which makes AGK choose a higher resolution with xvid.
As an example I have just done an encode of chapter 14 and 15 of The Matrix Reloaded (where Neo fights all the agent Smith's). The size of the vob file was 432 MB and I chose custom size: 100 MB and abr Mp3 128 kbps.
The Divx compressibility percentage was 80,68 and the chosen resolution was 640x256.
The Xvid compressibility percentage was 100,12 and the chosen resolution was 704x288, which resulted in a predicted comptest value of 80,91.
This is probably totally normal, and it is not like that there's anything wrong with the quality for either Divx or Xvid. I just thought that Xvid would produce the lowest comptest percentage, as I presume it starts out with a less compressible matrix than the H.263 used by Divx. Is this wrong? And why is the compressibility test higher for Xvid? I sincerely hope that this question hasn’t been answered already - I’ve been unable to find the answer using search.
Lastly a suggestion for the log file: would it be possible for AGK to output the matrix chosen to the log file when using Xvid? It is of no real use to the average user, but it still would be nice to know.
Regards,
Mnl
As an example I have just done an encode of chapter 14 and 15 of The Matrix Reloaded (where Neo fights all the agent Smith's). The size of the vob file was 432 MB and I chose custom size: 100 MB and abr Mp3 128 kbps.
The Divx compressibility percentage was 80,68 and the chosen resolution was 640x256.
The Xvid compressibility percentage was 100,12 and the chosen resolution was 704x288, which resulted in a predicted comptest value of 80,91.
This is probably totally normal, and it is not like that there's anything wrong with the quality for either Divx or Xvid. I just thought that Xvid would produce the lowest comptest percentage, as I presume it starts out with a less compressible matrix than the H.263 used by Divx. Is this wrong? And why is the compressibility test higher for Xvid? I sincerely hope that this question hasn’t been answered already - I’ve been unable to find the answer using search.
Lastly a suggestion for the log file: would it be possible for AGK to output the matrix chosen to the log file when using Xvid? It is of no real use to the average user, but it still would be nice to know.
Regards,
Mnl