[mythtv-users] Transcoding profiles

Paul Gardiner lists at glidos.net
Thu May 26 10:00:16 UTC 2011

On 26/05/2011 10:46, Dave Sp wrote:
> On Sun, May 22, 2011 at 6:43 PM, Raymond Wagner <raymond at wagnerrp.com
> <mailto:raymond at wagnerrp.com>> wrote:
>     On 5/22/2011 18:36, Dave Sp wrote:
>>     On Fri, May 20, 2011 at 3:05 AM, Paul Gardiner <lists at glidos.net
>>     <mailto:lists at glidos.net>> wrote:
>>         On 19/05/2011 17:12, Raymond Wagner wrote:
>>         > Not directly, no.  However you can get mythtranscode to act
>>         as a raw
>>         > frame server to another application that can.  See nuvexport
>>         for an
>>         > example on how to do this.
>>         If someone has figured out how to drive HandBrake like that,
>>         can they
>>         please post how it's done?
>>         With SD, I used to use lossless transcode to cut adverts and then
>>         archive with HandBrake, but now most of my content is HD, I've
>>         more or less given up.
>>     For my HD recordings, I use mythtranscode with the --mpeg2 and
>>     --honorcutlist options to create a new file, then send that to
>>     HandBrakeCLI with "--preset Normal" to create the final video.
>>     For me, Handbrake's output file is around 1/10th the size of its
>>     input file.
>     That doesn't sound right.  By clipping commercials, you're going to
>     chop off maybe 35% of a recording.  MPEG2 to H264 is going to get
>     you another 2-3x.  I could see 1/5th the original recording, but not
>     1/10th unless you're downscaling the video.
> I'll use last Sunday's Family Guy (hour long) as an example.
> Original recording:
> 1 hour, 3 minutes.  MPEG-2 (TS).  1280x720.  15.5Mbps bitrate.  6.9GB
> file size.
> Hand-cut commercials.  After mythtranscode with --mpeg2 and
> --honorcutlist options:
> 43 min, 30 sec.  MPEG-2 (PS).  1280x720.  15.5Mbps bitrate.  4.8GB file
> size.
> After HandBrakeCLI with "--preset Normal":
> 43 min, 30 sec.  MPEG-4.  1280x720.  Variable bitrate (overall
> 2.6Kbps).  797MB file size.
> The resulting file size is 12% of the original before transcode.  And
> the final video doesn't have any artifacts that I can see.

I've seen similar stunning results from Handbrake, but the problem is
to find a procedure like that when the starting point is H264,
without an intermediate step throwing away some of the quality and
without creating huge temporary files.


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