[mythtv-users] Is anyone transcoding BBC HD using Mencoder?
mikep at randomtraveller.org.uk
Fri Mar 26 15:28:39 UTC 2010
> Play source to determine start and endposition.
> Rename source.mpg source.ts, as tsmuxer will not recognize the file as
> being a ts.
> tsMuxerGUI `pwd`/source.ts
> Disable the NAR-audio, if not needed of course, select "Split & cut",
> enable "Cutting" add Start End values, select Demux, select "Start
> You now will have source.track_5500.264 and source.track_5501.ac3 which
> are perfectly synced sources, which means if merging with mkvmerge or
> tsmuxer or ffmpeg there will be NO delay for audio or video.
> You now only have to encode the cutted parts, not with the overlapping
> parts, with whatever tool you like.
> On an AMD Athlon(tm) 64 X2 Dual Core Processor 4000+ it encodes the
> file to 1280x720 at 10fps, so it takes 2.5hours for a 1hour program,
> with following encoding parameters:
> ffmpeg -i source.track_5500.264 -an -vcodec libx264 -threads 0 -b 2872k
> -deinterlace -flags +loop -coder 1 -refs 2 -deblockalpha 0 -deblockbeta
> 0 -partitions +parti4x4+partp8x8+parti8x8+partb8x8 -me_method umh -subq
> 4 -me_range 16 -flags2 +dct8x8+mixed_refs -cmp +chroma -bf 0 -b_strategy
> 1 -g 250 -keyint_min 25 -sc_threshold 40 -maxrate 2500k -qmin 22 -qmax
> 27 -s 1280x720 -f rawvideo source720p.264
> I want 'quality', hence qmax 27, with 'low bitrates' 2872k. If it's a
> low movement source q will be at 22, not wasting bits on, not perceived
> by me, 'better' quality. While giving adequate quality, -qmax 27, at
> lowest possible bitrate in fast moving scenes.
> Merge the encoded results with mkvmerge or MP4Box or tsMuxerGUI to what
> you want. If you want subtitles, you can extract them with projectx.
> Doing this for BBCHD, the command is:
> projectx -ini ~/888.ini -id 0x157F -demux -out . $1
> where 888.ini is a renamed X.ini from projectx where teletext page 888
> is defined as the wanted page#.
> You'll get the uncutted length of the subtitles. With mmg, the gui for
> mkvmerge, you can define a negative delay for the subtitles, so you're
> able to get them in sync.
> mediainfo tells me about "a BBCHD-sourcefile' that
> Video delay : -1176
> By using tsMuxerGUI for cutting and demuxing, you don't have to fiddle
> with these values sources are 'padded' to get them in sync.
I hope you add this to the wiki. Very interesting.
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