[mythtv] If you use the transcoder please read

[Steele Price]

While your at it... could you please tie in files in the video list to be
available for transcoding as well?  I have a bunch of files in there that I
would like to archive, but I am having to do it all pretty much manually.
It would be nice to be able to batch these up for transcoding from a menu
(like a whole season of a tv series) then trancode them off to some archive
format that is smaller than mpeg2.

Steele Price
CTO
Digital Dreamhop
http://xtcp.net


-----Original Message-----
From: mythtv-dev-bounces at mythtv.org
[mailto:mythtv-dev-bounces at mythtv.org]On Behalf Of Geoffrey Hausheer
Sent: Thursday, September 11, 2003 12:45 PM
To: mythtv-dev at mythtv.org
Subject: [mythtv] If you use the transcoder please read


If you haven't noticed, the manner of setting up profiles is getting
ready to change.  The new method is much more flexible/powerful, and it
gives us the ability to add more flexibility to the transcoder as well.

I have two options as to how the transcoder will work (there may be
others, and I'm open to sugestions).

Today there is one transcoder profile.  If you use the transcoder, that
is the profile you get.

In the future there will be multiple transcoder profiles.  There are two
ways to go about this:
1) There is a transcoder profile that maps to each of 'High', 'Low',
'Default', and 'TV'.  This is equivalent to there being a Transcoder
profile group.  Any recording done at 'High' regardless of the card will
be transcoded with the 'High' transcoder settings.

2) Each card-type has a transcoder profile.  This means that all PVR
cards will use the same transcoder settings, regardless of what the
recording settings are.

Neither of these solutions is perfect, and they both have pretty much the
same problem:  You might have 'High' set to 640x480 for bttv, and 720x480
for PVR.  If you select a fixed video-bitrate, then one of your
transcodings will not be at the optimal setting.  this can be mitigated
by allwing myth to auto-scale the bitrate based on resolution, but it
isn't very intuitive.  (2) suffers more from this, as it is more likely
that 'High' quality settings will be comparable across profiles, than
that all of the 'MPEG' profiles will be comparable.  (1) Has a second
problem.  When you start an interactive transcoding, we don't know what
profile it is associated with.  I can detect the recording type (MPEG2,
MPEG4, RTJpeg), but there is no way to map that to a quality level.  If I
go for option (2), I can choose a profile based on the recording format.


If I don't get a good reason to do otherwise, I'll implement (2).  It is
easier to make the transcoder behave consistantly with this method.

Also, I plan to allow auto-transcoding on a per-profile basis.  So you
can autotranscode only your RTJpeg encodings if that is what you want.

Anyone who has a strong opinion has until the time I finish the patch to
convince me to change my mind...unless it's Isaac, in which case, I'll
just do it his way :)

.Geoff
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