Some x264 codec encoding features

[LeoKac]

Please, answer these several questions: (NOTE, I am the guy who doesn't care about encoding speed, just need highest quality)

1) What is "DPB (Decoded Picture Buffer) size", and which value is the best to adjust? (The value is from 0 to 16)

2) Enable or disable Intra refresh? (This diasables IDR-frames)

3) Enable or disable Weighted B-frame references?

4) (This is from H.264 codec) Which value should I adjust on "Mark Every * I-frame as IDR" (The value is from 0 to 100'000)
http://img9.imageshack.us/img9/8241/h12z.png
5) Enable or disable "Fixed I-Frames Distance"?

6) Enable or disable "Adaptive B-Frame Placement?"

Thanks....

[vivan]

(NOTE, I am the guy who doesn't care about encoding speed, just need highest quality)Then use --preset placebo (http://mewiki.project357.com/wiki/X264_Settings#preset)...

[LoRd_MuldeR]

Please, answer these several questions: (NOTE, I am the guy who doesn't care about encoding speed, just need highest quality)

1) What is "DPB (Decoded Picture Buffer) size", and which value is the best to adjust? (The value is from 0 to 16)

The DPB is not an encoder option, but a part of the decoder. However some encoder options, e.g. the number of reference frames, influence the size of the DPB that will be required to decode your video! Each H.264 Level has a certain (maximum) DPB size. As the size of the DBP is defined in bytes (and not in frames!), the maximum number of reference frames you can use depends on both, the desired H.264 Level and the resolution (i.e. frame size) of the video.

2) Enable or disable Intra refresh? (This diasables IDR-frames)

Your probably mean "Periodic Intra Refresh", which will disable the creation of IDR-Frames.

With this option enabled, you won't be able to seek in the video - at least not in the "classical" way. You can't start playback at an IDR-Frame, because there aren't any. Instead you can start decoding the video at any random point, but it will take some time for the video to "recover". While the video is still "recovering", you either get scrambled output or no output at all, depending on the player software.

This feature is good for some streaming applications, but you usually don't want that for "local" video files!

3) Enable or disable Weighted B-frame references?

Enable ;)

4) (This is from H.264 codec) Which value should I adjust on "Mark Every * I-frame as IDR"

No idea what this refers to. Doesn't seem to be an x264 option (that I am aware of). Maybe refers to some other H.264 encoder?

(AFAIK, x264 will only place IDR-Frames. It doesn't place Non-IDR I-Frames, except when a scenecut is triggered before the minimum key-frame interval was reached)

5) Enable or disable "Fixed I-Frames Distance"?

This effectively disables "Scene cut" detection and instead places the IDR-Frames at fixed distance.

You normally don't want fixed distance IDR-Frames, for obvious reasons. Instead, keep scenecut detection enabled!

6) Enable or disable "Adaptive B-Frame Placement?"

If you don't enable "Adaptive B-Frame Placement", then P-/B-Frames will be placed with a fixed pattern, instead of selecting the optimal frame-type for each frame.

Obviously you normally want the adaptive B-Frame placement... (except when encoding speed is the only thing that matters)