x264 encoding options in ffmpeg, corresponding relationships

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x264 h.264/mpeg-4 AVC Encoder Wrapper. This encoder requires the presence of the libx264 headers and library during configuration. You need to explicitly configure the build with--enable-libx264. LIBX264 supports an impressive number of features, including 8x8 and 4x4 adaptive Spatial transform, adaptive b-frame plac Ement, Cavlc/cabac entropy Coding, interlacing (MBAFF), lossless mode, Psy optimizations for detail retention (adaptive qu Antization, Psy-rd, Psy-trellis). Many libx264 encoder options is mapped to FFmpeg Global codec options, while unique encoder options is provided through Private options. Additionally the x264opts and X264-params private options allows one to pass a list of Key=value tuples as accepted by The libx264 x264_param_parse function.
The LIBX264RGB encoder is the same as libx264, except it accepts packed RGB pixel formats as input instead of YUV. 17.8.1 supported Pixel Formatsx264 supports 8-to 10-bit color spaces. The exact bit depth is controlled at x264 ' s configure time. FFmpeg only supports one bit depth in one particular build. In the other words, it was not possible to build one FFmpeg with multiple versions of x264 with different bit depths. 17.8.2 OptionsThe following options is supported by the libx264 wrapper. The x264-equivalent options or values is listed in parentheses brackets for easy migration. Options for x264 in parentheses
To reduce the duplication of documentation, only the private options and some others requiring special attention is docum ented here. For the documentation of the undocumented generic options, see the Codec options chapter. To get a more accurate and extensive documentation of the libx264 options, invoke the command x264--FULLHELP or consult The libx264 documentation. B ( bitrate )Set bitrate in bits/s. Note that FFmpeg ' s B option was expressed in bits/s, while x264 ' s bitrate was in kilo bits/s.

BF ( Bframes ) g ( Keyint ) Qmin ( Qpmin )Minimum Quantizer Scale. Qmax ( Qpmax )Maximum Quantizer Scale. Qdiff ( Qpstep )Maximum difference between quantizer scales. Qblur ( Qblur )Quantizer curve Blur Qcomp ( Qcomp )Quantizer curve Compression factor Refs ( ref )Number of reference frames each p-frame can use. The range is from 0-16. Sc_threshold ( Scenecut )Sets the threshold for the scene change detection. Trellis ( Trellis )Performs Trellis quantization to increase efficiency. Enabled by default. NR ( nr ) Me_range ( Merange )Maximum range of the motion search in pixels. Me_method ( Me )Set motion Estimation method. Possible values in the decreasing order of speed: ' Dia ( Dia ) ' ' EPZs ( Dia ) 'Diamond Search with radius 1 (fastest). ' EPZs ' is a alias for ' Dia '. ' Hex ( Hex ) 'Hexagonal Search with radius 2. ' UMH ( UMH ) 'Uneven Multi-hexagon search. ' ESA ( ESA ) 'Exhaustive search. Exhaustive search ' Tesa ( Tesa ) 'Hadamard exhaustive search (slowest). Forced-idrNormally, when forcing a i-frame type, the encoder can select any type of i-frame. This option forces it to choose an idr-frame. SUBQ ( SUBME )Sub-pixel motion Estimation method. B_strategy ( b-adapt )Adaptive b-frame Placement decision algorithm. Use is on First-pass. Keyint_min ( Min-keyint )Minimum GOP size.
CoderSet Entropy Encoder. Possible values: ' AC 'Enable CA BAC. ' VLC 'Enable CA VLC and disable CABAC. It generates the same effect as x264 ' s--NO-CABAC option. CMPSet Full pixel motion estimation comparison algorithm. Possible values: ' Chroma 'Enable Chroma in motion estimation. ' Sad 'Ignore Chroma in motion estimation. It generates the same effect as x264 ' s--no-chroma-me