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Changes between Version 6 and Version 7 of Encodings


Ignore:
Timestamp:
03/16/13 04:25:53 (9 years ago)
Author:
Antoine Martin
Comment:

typos

Legend:

Unmodified
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  • Encodings

    v6 v7  
    3333=== Profiles ===
    3434(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}}}
     35x264 supports the following profiles: {{{baseline}}}, {{{main}}}, {{{high}}}, {{{high10}}}, {{{high422}}} and {{{high444}}}.
     36
    3637At present, we use {{{high}}} or better by default unless the client overrides it.
    3738
     
    3940=== Quality Option ===
    4041What 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 {{{YUB420}}}. 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).
    4243* 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).
    4344* some builds against older versions of libav/ffmpeg only support {{{YUV420}}},