[mythtv] mythtranscode: potential optimization

[Mark Steckel]

At 12:30 PM 11/27/2007, you wrote:
>mythtranscode behaves differently depending on whether you told it to do
>a normal transcode which is what Chris's example is doing or a lossless
>transcode with the --mpeg2 option which it looks like you are doing?

Ah... You are correct. I am specifying --mpeg2 whereas Chris' example does not.


>The
>last time I looked the lossless transcoder scans though the entire file
>at the end to create some sort of map file that as far as I know isn't
>actually used by anything. It may also scan though the entire file
>during the actual processing as well. The lossless transcoder is usually
>pretty quick though?

There is a *big* time difference. Using the same 2.2GB mpeg input file

   with --mpeg2: 45 seconds
   without --mpeg2: 0.5 seconds

Since I am interested in the video quality of the output file I 
presumed that --mpeg2 was necessary. However, I ran 'cmp' on the 
resulting files produced with and w/o --mpeg2, and it showed no 
difference. So, at least in this case I can run mythtranscode w/o --mpeg2.

However, while I have a solution to my particular issue, it does 
appear that using --mpeg2 causes extra work to be performed.

Thanks for everyone's assistance!

Mark