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Changes between Version 1 and Version 2 of Encodings/x264


Ignore:
Timestamp:
11/01/13 12:30:18 (5 years ago)
Author:
Antoine Martin
Comment:

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  • Encodings/x264

    v1 v2  
    11= x264 Encoding =
    2 (see [http://en.wikipedia.org/wiki/H.264 wikipedia H.264])
    3 x264 is the encoding that supports the most options and tunings, and the default option when available because it offers the best performance and compression out of the box.
     2x264 is the encoding that supports the most options and tunings. It is the default encoding used when it is available because it offers the best performance and compression out of the box.
    43
    5 Quality/speed and minimum quality/speed can be set via the command line (and the latter can also be changed at runtime via the tray applet)
     4Quality/speed and minimum quality/speed can be set via the command line or via the tray menu.
    65Note that even when using the x264 encoding, some small screen updates may get sent as png or rgb24 to save time/bandwidth (not encoding a full frame).
    76
    8 For more information on x264 options, see [http://www.avidemux.org/admWiki/doku.php?id=tutorial:h.264 H.264 encoding guide]
     7== Links ==
     8* [http://www.avidemux.org/admWiki/doku.php?id=tutorial:h.264 H.264 encoding guide] for more information on x264 options
     9* [http://en.wikipedia.org/wiki/H.264 wikipedia H.264]
     10The following wiki pages are also relevant:
     11* [WindowRefresh] - when and how the screen updates are processed
     12* [Encodings] - all the picture encodings available
     13* [CSC] - the Colourspace conversion step
    914
    10 === Profiles ===
     15
     16== Profiles ==
    1117(see [http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles wikipedia h264 profiles])
    1218x264 supports the following profiles: {{{baseline}}}, {{{main}}}, {{{high}}}, {{{high10}}}, {{{high422}}} and {{{high444}}}.
     
    1521
    1622
    17 === Quality Option ===
     23== Quality Option ==
    1824What this does should be obvious (in x264 speak, this controls the {{{rc.f_rf_constant}}} parameter), but it is more complicated than you think:
    1925* 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).