Changes between Version 6 and Version 7 of Encodings
- Timestamp:
- 03/16/13 04:25:53 (9 years ago)
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Encodings
v6 v7 33 33 === Profiles === 34 34 (see [http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles wikipedia h264 profiles]) 35 x264 supports the following profiles: {{{baseline}}}, {{{main}}}, {{{high}}}, {{{high10}}}, {{{high422}}} and {{{high444}}} 35 x264 supports the following profiles: {{{baseline}}}, {{{main}}}, {{{high}}}, {{{high10}}}, {{{high422}}} and {{{high444}}}. 36 36 37 At present, we use {{{high}}} or better by default unless the client overrides it. 37 38 … … 39 40 === Quality Option === 40 41 What this does should be obvious (in x264 speak, this controls the {{{rc.f_rf_constant}}} parameter), but it is more complicated than you think: 41 * we support 3 different colourspace modes: YUV420, YUV422 and YUV444 and this affects the quality of the picture too. (YUV420 is used for lowest quality settings). {{{YUV444}}} uses roughly twice as much bandwidth as {{{YU B420}}}. Switching from one mode to another is expensive, as we then need to send a new key frame and re-initialize both the encoder and the decoder - so the thresholds for going up to the next mode are not the same as the thresholds for going down to the next mode (prevents a yoyo effect).42 * we support 3 different colourspace modes: YUV420, YUV422 and YUV444 and this affects the quality of the picture too. (YUV420 is used for lowest quality settings). {{{YUV444}}} uses roughly twice as much bandwidth as {{{YUV420}}}. Switching from one mode to another is expensive, as we then need to send a new key frame and re-initialize both the encoder and the decoder - so the thresholds for going up to the next mode are not the same as the thresholds for going down to the next mode (prevents a yoyo effect). 42 43 * not all modes are supported by all profiles, so we need to switch to a different profile to support {{{YUV422}}} ({{{high422}}} or {{{high444}}}) and {{{YUV444}}} ({{{high444}}} only). 43 44 * some builds against older versions of libav/ffmpeg only support {{{YUV420}}},