[MEncoder-users] Dolby downmix

[Rolf Ernst]

Meant to say 'loose the timing info instead of 'use the timing info', sorry.

On Tue, Dec 28, 2010 at 5:18 PM, Rolf Ernst
<rolf.ernst at silverlightning.org>wrote:

> Rolf Ernst <rolf.ernst <at> silverlightning.org> writes:
>>
>>
>>  Now I take the 5.1 6 channel signal and want to downmix to two channel
>> surround which preserves at least some of the surround information
>>
>>  And as I tried to explain in my first mail in this thread I don't think this
>> works with MPlayer (I didn't read the sources, but the manual clearly denies it.)
>>
>>
>>  As for the interlacing
>>
>>  Carl,
>>
>> I uploaded sample sample_HDPVR_60-24fps_conversion_av_glitch.M2TS. I cut
>> around it so ignore start and/or end glitch. At pretty much exactly 15
>> seconds into it is a capturing glitch (note they are rare, maybe two or
>> three in an hour). You will see that the whole file plays back without a
>> hitch using mplayer or windows media player or whatever other
>> semi-intelligent player there is. Perfect sync from beginning to end.
>>
>
> I use the following command line to convert it to 23.976 fps:
>
> mencoder sample_HDPVR_60-24fps_conversion_av_glitch.M2TS  -o sample.avi
> -ovc x264 -x264encopts
> threads=0:bframes=5:b-adapt=2:partitions=all:cabac:nopsnr:nossim:deblock:mixed_refs:frameref=6:weight_b:b_pyramid=normal:me=umh:merange=16:subme=6:analyse=all:8x8dct=1:deblock:trellis=1:psy-rd=1,1:no-fast-pskip=1:crf=23
> -oac faac -faacopts br=160:mpeg=4:object=1 -vf
> tinterlace=4,softskip,harddup,filmdint=io=30:24/fast=0,scale=720:480 -noskip
> -mc 0 -fps 60000/1001 -ofps 24000/1001 -demuxer lavf
>
> You can play this back and it has aac audio and it has perfect sync even
> across the glitch (this is why I like mencoder so much and believe it is
> superior in some ways to ffmpeg).
>
> Now, if you demultiplex the elementary streams and try to remultiplex them
> into say a matroska container your video will be out of sync after the
> glitch (after 15 seconds abruptly). If you use any other conversion method
> than the one outlined in my command line (ignoring, of course, the codec)
> you will get jerky video if not immediately then after the flitch. A simple
> filmdint will not do. However, this method is rock-solid. I have used it for
> dozens of episodes.
>
> If you can show me any way on how to do what I did there, i.e. scale from
> 60fps progressive down to 24 fps progressive with perfect frame accuracy
> across the glitch, keeping perfect a/v sync with ffmpeg and Dolby downmix to
> 2 channels I would be very interested. With mencoder I discard the channel
> info with the above command line and apparently there is no way around it. I
> know of no way of how to even reencode the input file (keeping it a 60 fps,
> keeping the video stream and only converting the audio stream if necessary)
> using any means. The problem is that as soon as I demultiplex the audio and
> encode it to aac outside using any given tool I use the timing info and the
> mutiplexer has to assume a frame rate (which is not correct right after the
> glitch).
>
> Ideas are appreciated.
>



-- 
/re

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