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Old 26th February 2007, 21:27   #1  |  Link
agilpwc
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x264 parameters / decode speed

Which of the x264 parameters or options make a video harder to decode?

What I'm looking for is the best parameters for a video that will be played back on a older computer. For example I have some 1280x720 videos that I'm trying to encode and even my dual core laptop has trouble playing it back, using the inefficient QT. Of course with VLC no problem, but I want to distrubute the video.

currently I've come up with
--bitrate 2500 --direct temporal --subme 6 --analyse p8x8,b8x8,i4x4,p4x4 --no-cabac --me dia --threads auto --thread-input --progress --no-psnr --no-ssim

For example, I know subme 6 slows encode time, but does it slow decode time?
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Old 26th February 2007, 21:40   #2  |  Link
shon3i
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cabac slow down decoding process
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Old 26th February 2007, 22:15   #3  |  Link
Manao
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Major speed factors ( from the most important to the least )
- cabac
- deblocking
- resolution
- bitrate
- bframes
- p4x4
- i4x4
- i8x8
- 8x8

No effect at all ( quality settings )
- subme
- me
- threads
- trellis
- ...
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Old 27th February 2007, 10:29   #4  |  Link
Dethis
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Just add to the above that cabac's influence in decoding speed is not steady but almost totally proportional to the bitrate.
So the conclusion is that when we encode with cabac on, the bitrate is the major factor in decoding speed.
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Old 28th February 2007, 03:40   #5  |  Link
DeathTheSheep
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I've also found (at least with CoreAVC plugin for Win32 TCPMP 0.72rc1) that a stream with 16 references decoded almost 10% more slowly than a stream with similar encoding settings but with 1 reference (mixed).
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Old 2nd March 2007, 18:59   #6  |  Link
bond
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Quote:
Originally Posted by agilpwc View Post
Which of the x264 parameters or options make a video harder to decode?

What I'm looking for is the best parameters for a video that will be played back on a older computer. For example I have some 1280x720 videos that I'm trying to encode and even my dual core laptop has trouble playing it back, using the inefficient QT. Of course with VLC no problem, but I want to distrubute the video.

currently I've come up with
--bitrate 2500 --direct temporal --subme 6 --analyse p8x8,b8x8,i4x4,p4x4 --no-cabac --me dia --threads auto --thread-input --progress --no-psnr --no-ssim

For example, I know subme 6 slows encode time, but does it slow decode time?
check the decoder comparison sticky for getting an idea on how things influence decoding
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