[mythtv] Mythtranscode .mpg => .mpg not .mpg => .nuv

Paul Wheeler paulrwheeler at gmail.com
Fri Nov 4 03:46:13 EST 2005


This sounds good, I will have a go this weekend (may have to be sunday) with
some uk dvb streams and let you know how i got on. I will also try and get
you an example stream with two audio tracks and subtitles for if you feel
like playing ;-).


On 11/3/05, Geoffrey Hausheer <mythtv0368 at phracturedblue.com> wrote:
> Okay, here we go:
> http://www.pblue.org/myth/mpeg2stuff.tgz
> Follow the directions in README to build it.
> The code has basically the same features as the last version I posted,
> but has been completely rewritten and more thoroughly tested. I'm
> still experiencing some weirdness with ATSC video, but it seems to be
> only in the last few frames.
> I still don't support discontinuous PTS, and haven't figured out an
> elegant way to do so yet.
> Replex doesn't support subtitles, so those won't work either.
> I haven't tried it on multiple audio-streams yet, as I don't have any
> mpegs that look like that, but it should be supported.
> There is one useful command line switch: -no3to2
> This tells the utility to remove all 3:2 pulldown (telecine) and
> enforce a strict frame-rate. It should generate a MPEG2 stream which
> can be demuxed/remuxed cleanly is needed, though the picture won't be
> quite as smooth (3:2 adds additional half frames (fields), allowing
> for smoother playback).
> There is also a -fixup switch which will enforce correct PTS (turning
> on -no3to2 will automatically enable this)
> If a PTS discrepency is detected, extra I-frames are added to buffer
> the video stream to stay in sync with the audio stream. It turns out
> you can't use a P-frame here because there is no way to know which
> macro-blocks are present, and mpeg2 doesn't allow you to predict a
> macro-block which wasn't in the previous frame.
> I plan to add support for opportunistically using 3:2 instead of
> building frames when -fixup is set but -no3to2 isn't, but am not quite
> there yet.
> As I said in my previous mail, this utility uses:
> avformat to get ES frames
> libmpeg2 to process video frames (and decode the picture as needed)
> replex to multiplex the final result.
> It seems to work fine with myth's libmpeg2 and libav*, but I needed to
> patch replex to fix several bugs, so that is included in the above
> archive.
> I could really use some feedback on how well it works, and, perhaps
> example streams where it doesn't.
> .Geoff
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