[mythtv-users] Struggling with MythArchive

[Paul Harrison]

On 03/01/13 21:24, John Pilkington wrote:
>
>>
>> The command line that I quoted in #11297 was
>>
>>   mythffmpeg -threads 2 -v verbose -i
>> "/home/john/Mythrecs/1102_20121207205600.mpg" -target pal-dvd -b:v 6000k
>> -s 720x576 -acodec mp2 -b:a 256k -ac 2 -aspect 16:9
>> "/mnt/MythOnRoot/Mytharch_work/work/1/newfile2.mpg"
>>
>> That worked, but you may want to change mp2 to ac3, and it uses only the
>> main stereo audio channel.
>>
>
> This was for re-encoding a BBC-HD  DVB-T2 recording to a DVD-type 
> format. On my "Centrino Duo" laptop ~2006 I typically see 25 to 30 
> fps.  The -b:v parameter seems to be ignored, or more likely treated 
> as an upper limit; the output size is probably determined by a q value 
> typically shown as 2.0 that is likely to be part of the pal-dvd 
> parameter package.  It's probably explained somewhere in the ffmpeg 
> docs but my Google-fu didn't find it.
>
> Another comment:  if the output is further shrunk by m2vrequantiser 
> within MythArchive, the shrink factor is exact. Usually, when I start 
> from DVB-T SD, there's an overshoot by around 1 percent.
>
> HTH
>
> John P

I got mythffmeg to complete OK only for mplex to fail early causing the 
dreaded 'Cannot jump to chapter 3 of title 1, only 2 exist' error message.

I did an experiment to see if the dvdauthor would accept the mpg file 
produced by mythffmeg directly without having to do the demux and remux 
steps and it seemed to work fine. This got me thinking it may be 
possible to simplify the whole thing and just use mythtrancode in fifo 
mode to decode and cut the file and pass the audio and video fifos to 
mythffmpeg to re-encode the result to a DVD compatible vob. This would 
remove the need for ProjectX and mplex to do the cutting, demuxing and 
remuxing.

It worked fine up to the very end where mythtrancode threw a decoding 
error on the last frame and promptly segfaulted. At this point I gave up 
but if you want to experiment here are the commands I used.

In one terminal run ( add --honorcutlist if you want to cut using the 
cutlist) :-
mythtranscode --profile 27 --chanid 6050 --starttime 20121225214400 
--fifodir /media/mytharchive/work/

And in another run:-
mythffmpeg -threads 4  -f rawvideo -pix_fmt yuv420p  -s 1920x1080 
-aspect 16:9 -r 25  -i /media/mytharchive/work/vidout -f s16le -ar 48000 
-ac 2 -i /media/mytharchive/work/audout  -target pal-dvd  -r pal -b:v 
4771k -s 720x576 -acodec ac3 -ab 192k -ac 2 -copyts -aspect 16:9  
"/media/mytharchive/work/1/final.vob"

If all goes well you should be left with a final.vob that can be passed 
to dvdauthor to create a DVD.

Paul H.