Changes between Version 2 and Version 3 of Encodings

Timestamp:

03/15/13 06:36:24 (8 years ago)

Author:

Antoine Martin

Comment:

--

Encodings

@@ -17 +17 @@
 Here are some rough guidelines:
 * on LANs with 100MBit/s or higher, use fast lossy encodings: either rgb24 or png
-* otherwise, choose x264 and tune the speed/quality to suit your needs
+* otherwise, choose x264 and tune the speed/quality to suit your needs (see below)
 The other encodings are somewhat less useful:
 * vpx is similar to x264 but it does not support speed and quality tuning
-* webm is single image subset of vpx, and therefore lacks [http://en.wikipedia.org/wiki/Intra-frame intra-frame] compression
+* webm is single image subset of vpx, and therefore lacks [http://en.wikipedia.org/wiki/Intra-frame intra-frame] compression - but latency is good
 * jpeg gives lower size/quality than other lossy encodings
 
+----
+
 == x264 specifics ==
+(see [http://en.wikipedia.org/wiki/H.264 wikipedia H.264])
 x264 is the encoding that supports the most options and tunings.
-Quality/speed and minimum quality/speed can be set via the command line (and the latters can also be changed at runtime via the tray applet)
-Note that even when using the x264 encoding, some small screen updates may get sent as png or rgb24 to save time/bandwidth.
+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)
+Note 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).
 
-=== Profile ===
+=== Profiles ===
+(see [http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles wikipedia h264 profiles])
 x264 supports the following profiles: {{{baseline}}}, {{{main}}}, {{{high}}}, {{{high10}}}, {{{high422}}} and {{{high444}}}
 At present, we use {{{high}}} or better by default unless the client overrides it.
@@ -42 +46 @@
 
 === Speed Option ===
-This option, shown as "latency" via the tray menu, controls how hard the encoder is going to work at compressing the picture. Working harder means lower bandwidth, but higher latency.
-
-
+This option, shown as "latency" via the tray menu, controls how hard the encoder is going to work at compressing the picture. Working harder means lower bandwidth, but also higher latency.
+x264 supports the following speed settings: {{{ultrafast}}}, {{{superfast}}}, {{{veryfast}}}, {{{faster}}}, {{{fast}}}, {{{medium}}}, {{{slow}}}, {{{slower}}}, {{{veryslow}}} and {{{placebo}}}.
+xpra maps the 100% to 0% speed option from {{{superfast}}} to {{{slower}}} only.
+{{{veryslow}}} and {{{placebo}}} are not particularly useful (diminishing returns: much much slower and without sufficient savings for real-time use).
+{{{ultrafast}}} is not available because setting the encoder to this setting has side-effects which prevents other settings from behaving as they should if the option is later changed. And in theory, {{{superfast}}} is almost as good.