Note that Baseline Profile, such as that used by iPods, does not support B-frames. This parameter simply serves to limit the max number of B-frames. Most, however, do not as a result, there is rarely any negative effect to setting this to the maximum (16) since x264 will, if B-adapt is used, automatically choose the best number of B-frames anyways. Some specific targets, such as HD-DVD and Blu-Ray, have limitations on the number of consecutive B-frames. This is not compatible with threading, however, and so -pre-scenecut is automatically activated when multiple encoding threads are used.ī-frames are a core element of H.264 and are more efficient in H.264 than any previous standard. Normal scenecut detection decides whether a frame is a scenecut after the frame is encoded, and if so then re-encodes the frame as an I-frame. Slightly faster (but less precise) scenecut detection. Recommended default: 25Īdjusts the sensitivity of x264's scenecut detection. Minimum GOP length, the minimum distance between I-frames. Very high GOP lengths will result in slightly more efficient compression, but will make seeking in the video somewhat more difficult. This determines the maximum distance between I-frames. Keyframe interval, also known as GOP length. This guide maps most of x264's options to FFmpeg's options along with detailed descriptions by x264 developer Dark_Shikari. Please see `avconv -h | less` or `ffmpeg -h | less` and scroll down to ' libx264 AVOptions:'.

Please Note: This guide will remain here for historic purposes but FFmpeg and libav now use libx264's internal -preset, -profile and -tune options.

X264 ffmpeg crf 25