Fast h264 decoders /optimal settings for x264

[xergon]

Hello,

after finding many threads about x264 ENCODERS, GPU-Acceleration and encoding speed I´m just left wondering what - right now -are the fastest available h264 decoders.

My second question:
x264 hast "fast" and "ultra fast" settings. These will mainly speed up encoding.
now, which settings will give good to very good video quality, while providing optimal DECODING speed?
Bitrate requirements will not be important, I just need a very fast lossy codec which will provide medicore bitrate efficiency at high picture quality.

It´s meant for vjing and media installations.

thx,
xergi

[nm]

after finding many threads about x264 ENCODERS, GPU-Acceleration and encoding speed I´m just left wondering what - right now -are the fastest available h264 decoders.

Software decoders? DiAVC (payware), CoreAVC (payware), DivX7 (gratis, freeware) and libavcodec from ffmpeg-mt (libre, free software) are pretty fast. Libavcodec from main FFmpeg branch is good too if you don't need frame-based multithreading.

My second question:
x264 hast "fast" and "ultra fast" settings. These will mainly speed up encoding.
now, which settings will give good to very good video quality, while providing optimal DECODING speed?
Bitrate requirements will not be important, I just need a very fast lossy codec which will provide medicore bitrate efficiency at high picture quality.

Bitrate has a significant effect on decoding speed, but you can usually gain speed by using CAVLC instead of CABAC. Deblocking is also a time-consuming process, so you may want to turn the inloop filter off. Try x264 --tune fastdecode ( --no-cabac --no-deblock --no-weightb --weightp 0).

[xergon]

thank you very much!

two more question:

a.) which of these decoders has an vfw codec? Divx yes, anything else?

b.) how can I tell an application to use a certain vfw codec?
There are still many vfw applications around (resolume, sony vegas, etc.), and i need to tell them which codec to use for h264 decoding.
so, how to tell vfw applications to use divx and not ffdshow or vice versa?

Greets,
Stefan

[poisondeathray]

b.) how can I tell an application to use a certain vfw codec?
There are still many vfw applications around (resolume, sony vegas, etc.), and i need to tell them which codec to use for h264 decoding.
so, how to tell vfw applications to use divx and not ffdshow or vice versa?


Often you cannot for applications that decode through vfw.

For example vegas, premiere, most NLE's you cannot change decoders even if you change your system vfw or directshow decoder

[Blue_MiSfit]

Yes. As far as I know Vegas and Premiere have their own decoders and don't actually use VFW decoders. They can use VFW encoders, but are often very finicky. Vegas certainly is!

IMO, your best bet is to encode your video to most closely resemble standards like AVCHD / AVC Intra.

Derek

[AlekseiV]

Somewhat related to this thread, what are settings that affect decoding speed; I want to set settings as high as possible but still allow easy decoding by e.g. flash players (my own hosting)

I am use:
--preset veryslow --bframes 3 --ref 5 --rc-lookahead 120
Is there anything I am setting that will hurt decoding importantly?

[nm]

Somewhat related to this thread, what are settings that affect decoding speed

The settings that increase decoding speed are those set by --tune fastdecode: --no-cabac --no-deblock --no-weightb --weightp 0. But I wouldn't set any of those if I was hosting files over the internet because they also reduce compression efficiency significantly.

Anyway, the most important factors are bitrate and resolution, so the problem is solved if you offer the files at multiple resolutions, which you need to do in any case. Properly encoded 480p should play fine on most machines and the quality can be much better than what Youtube offers at that resolution.

[Blue_MiSfit]

Indeed. If you're looking at extreme cases of very slow CPUs / crappy decoders, consider disabling CABAC. It hurts to suggest this because CABAC is so awesome, but it's also very tough to decode - compared to CAVLC anyway.

This is a trick I always use if I'm targeting QuickTime on Windows. Crappy decoder is crappy ><

I'm inspired now to look at just how much CABAC speeds up decode on (for example) libavcodec.... Hrrmmm, I smell an Excel sheet coming on...

Derek