[coherence-dev] (almost) success with Sony Bravia KDL-32W5500

[Alexander E. Patrakov]

Hi,

I have a Sony Bravia KDL-32W5500 TV set and want to use it to watch
films stored on my computer. For this purpose, I installed Coherence
(SVN r1407).

The documentation for my TV says that supported formats are: AVCHD, HDV,
MPEG2-PS. I know nothing about AVCHD or HDV, and MPEG-2 files straight
from a DVD play fine without transcoding. So, I tried to use the
transcoding feature of Coherence to play other files. It didn't work out
of the box, because it produces MPEG-TS. So, as a quick hack, I changed
the gstreamer pipeline in the MP2TSTranscoder class as follows:

self.pipeline = gst.parse_launch(
            "mplex format=3 vbr=true mux-bitrate=15360 bufsize=1024
name=mux %s ! decodebin2 name=d ! ffmpegcolorspace ! mpeg2enc format=3
bitrate=10000 constraints=false bufsize=1024 reduction-4x4=4
reduction-2x2=4 ! mux. d. ! queue ! audioconvert ! twolame ! mux."  %
self.uri)

The intention is to have a high-bitrate MPEG2-PS stream with the fastest
encoding options. Note that I had to remove the queue between twolame
and mux because otherwise it doesn't want to play. I also removed
several other redundant queues. "constraints=false" is needed for HDTV
resolutions (although the aspect ratio becomes wrong for 2.35:1 content
encoded as 1280x544). bufsize has to be increased from the default value
for the same reason (HDTV). "mplex" is needed, because "ffmux_mpeg"
produces streams that are playable only by ffmpeg-based players.

Still, there are some problems:

1) Coherence uses 100% CPU when doing nothing, and over 180% when
playing any clip (even SD). Looks like a busy-wait somewhere.
2) Audio and video sometimes get out of sync after skips.
3) If I stop and restart Coherence, it will appear as a different server
in the menu of my TV. Very annoying, given that the TV remembers all
previously seen servers and has a limit of 10-or so menu entries, after
which it refuses to recognize new servers.
4) I cannot seek in the transcoded streams.
5) It would be nice to avoid reencoding the file when it is sufficient
to remux it (e.g., H.264 + AC3 in MKV => AVCHD, but note that I don't
know where to get an AVCHD sample for testing if this would work and
could not produce a working sample myself with ffmpeg).

Unrelated to video:

6) Coherence doesn't list ape files in the TV menu, even though other
gstreamer-based applications can decode them to wav.

Are there any plans to fix these issues? Any patches for me to try?

-- 
Alexander E. Patrakov