[mythtv-users] Share your transcode settings!

Jeremy Jones jeremy.dwain.jones at gmail.com
Wed Jan 11 19:25:59 UTC 2012

On Wed, Jan 11, 2012 at 11:46 AM, Raymond Wagner <raymond at wagnerrp.com>wrote:

>  On 1/11/2012 12:35, Jeremy Jones wrote:
> On Wed, Jan 11, 2012 at 11:24 AM, Raymond Wagner <raymond at wagnerrp.com>wrote:
>>   On 1/11/2012 12:16, Jeremy Jones wrote:
>>>  I really like the results obtained by running mythtranscode, used in
>>> fifodir mode into ffmpeg. You still get to cut adverts out, plus
>>> you get full control of recompression. You can maintain interlace, or
>>> deinterlace and double the frame rate. My script is linked to from
>>> the mythtranscode wiki page: http://www.mythtv.org/wiki/Mythtranscode.
>>> May not do exactly what you want, but should be easy to alter.
>>  Can you change from HD to SD and still keep the Mpeg-ts container?  Or
>> does it have to go into a nuv?
>>  No and no.  FIFO mode in mythtranscode opens a pair of named pipes on
>> the filesystem, and feeds the raw audio and video streams into them.  These
>> pipes use the standard 64KB POSIX buffering, so as you pull data from them,
>> mythtranscode pushes more data into them, in FIFO ordering.  The video is
>> clipped, deinterlaced, cropped, and filtered however you have configured,
>> but it is not encoded nor is it multiplexed into any form of container.  It
>> is left up to you to do those things.
>>  Raymond,
>  I didn't realize how far over my head that post was until you explained
> what was going on.  Thanks for making it simple with the transcode wrapper
> you wrote.
> The transcode wrapper doesn't touch any of that stuff.

Right, I see now how poorly my writing described what I was thinking.  I
really just meant thanks for making the task of custom transcoding simple,
not that it did the FIFO stuff Paul and you described.  I actually did
understand enough to know that the wrapper didn't do that.

> All it does is give filenames for the user-chosen command to read from and
> output to, and then fix up the various details in the database to reference
> the new file.  What Paul Gardiner is using and what I described is called a
> frameserver.  It is intended to allow video processing to be pipelined
> through multiple applications, without having to waste disk space and disk
> IO on one or more intermediary files.  Nuvexport uses this mode internally,
> and a number of Windows tools such as MeGUI use AviSynth for similar
> purposes, but it is beyond the scope of most tasks that just wrap 'ffmpeg'
> or 'handbrakecli'.
> http://en.wikipedia.org/wiki/Frameserver
That helps on my understanding of what Paul is doing.  Is this something
that you would recommend for custom transcoding? What are the pro's and
cons of doing it that way?  Or asked another way, when would one want to do
that as opposed to using the wrapper with ffmpeg (or other  cli program)?
 Can you elaborate on the, 'beyond the scope' comment above?

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