[gstreamer-bugs] [Bug 607798] New: x264enc needs updating to support new features

GStreamer (bugzilla.gnome.org) bugzilla at gnome.org
Fri Jan 22 10:46:58 PST 2010

  GStreamer | gst-plugins-ugly | git

           Summary: x264enc needs updating to support new features
    Classification: Desktop
           Product: GStreamer
           Version: git
        OS/Version: All
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: Normal
         Component: gst-plugins-ugly
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: darkshikari at gmail.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
      GNOME target: ---
     GNOME version: ---

libx264 has recently added a lot of new features, many of which are not
available in x264enc.  Some examples:

1) x264 by default has a very large lookahead.  This can be disabled, of
course, but x264enc doesn't currently expose the options (sync-lookahead,
rc-lookahead, sliced-threads) in order to do it.

2) x264 now supports intra-refresh, an I-frame-less encoding mode for low
latency streaming.  Not only can this not be set, but it requires that
x264_picture_t->b_keyframe be used for signalling keyframes, not pic_type ==

3) A few variables that used to be booleans are now ints, e.g. b-adapt now has
3 modes (off, fast, optimal) to match ffmpeg's b-strategy, while it used to
only be "off" and "fast".  These variables aren't exposed through x264enc
either; one can only set off or fast currently.

It would also be extremely useful if x264enc supported the presets and/or tune
options present in x264.c, which provide a convenient way to adjust speed and
quality settings without messing with a large number of internal options.  This
would let a user set tune=zerolatency to turn off the lookaheads, as opposed to
going through 4 low-level options themselves.  This is less important than
supporting the new features though.

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