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danielgtaylor / arista

Arista Transcoder
http://www.transcoder.org/
GNU Lesser General Public License v2.1
120 stars 19 forks source link

Question about quality "1-10" #99

Open te-con-miel opened 13 years ago

te-con-miel commented 13 years ago

Hello,

I just want to known what is better for maximum quality "1"or "10"

quality=1 threads=%(threads)s speed=2

Also, in webm (vp8) with dual core cpu, when I change "threads=%" "for threads=2" conversion fail.

Finally, what about the "speed"? "speed=2" can be tweaked? more speed is = worst quality or just more cpu will be used?

Thank you very much Daniel, your app is great!

danielgtaylor commented 13 years ago

For the VP8 encoder the quality setting of 1 is worst, and 10 is best.

What error are you seeing when running with arista-gtk -v and using threads=2?

Speed controls internal VP8 stuff. Basically speed=0 is very slow but the best quality. 1 is in between while 2 is very fast but less quality (or more bits if using quality=X). As an example, if you used the settings of quality=5 speed=0 the final file may be 500kb and take 30 minutes to encode. If you use quality=5 speed=2 the final file might be 600kb and take 10 minutes to encode. Both files would look exactly the same to your eyes.

te-con-miel commented 13 years ago

Hello,

Mi error was use quality=6 threads=2(threads)s speed=2

Using: quality=6 threads=2 speed=2 is working fine.

With default vp8 preset the quality is not enough for covert divx/xvid to webm. The video is inferior compared to original divx and is very notorious.

Which parameters do you recommend to configure webm preset in order to obtain better video quality when rip divx to vp8?

Using "threads=2"

te-con-miel commented 13 years ago

Another comment: By default, 16 size for subtitles is too big, really.

Thank you.-

danielgtaylor commented 13 years ago

You can try quality=8 speed=2 threads=2. To save a little disk space you can change speed=2 to speed=1 but it will take longer to encode. The VP8 encoder is still very new and doesn't have a lot of optimizations, but Google and the FFmpeg guys are working on changing that, so stay tuned for psychovisual optimizations and such.

What size do you recommend for subtitles?

te-con-miel commented 13 years ago

Hello,

I did some tests and the recommended size should be 12

I'll try with 8-2-2.

Thank you very much.