[mythtv-users] Is anyone transcoding BBC HD using Mencoder?

Mike Perkins mikep at randomtraveller.org.uk
Fri Mar 26 15:28:39 UTC 2010

belcampo wrote:
> 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 
> demuxing".
> 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.


Mike Perkins

More information about the mythtv-users mailing list