[mythtv-users] Capture to DV or "uncompressed" AVI instead of MPEG-PS?

[Ian Trider]

On Apr 5, 2005 3:44 PM, Gregg Casillo <gcasillo at insightbb.com> wrote:

> Is it possible to capture to DV or "uncompressed" AVI instead of MPEG-2? I
> understand that these file types are massive, ~13GB/hr. I don't care. For me
> drive space is less problematic than file manipulation. I also know that this
> would mean a different capture card. Again, no problem there. I'll shell out
> anything to get away from MPEG-2 source files.


Sorry, no -- the PVR-250 only puts out compressed MPEG-2.  It -MAY- be
possible to get raw YUV2 (i.e. uncompressed, raw, video) out of it but
nobody really has much of any idea yet how it works -- search the
ivtv-devel archives if you want more info.

BTW, essentially if the problem you are referring to is audio sync, it
is because of how the PVR-250 outputs streams -- the video and audio
are aligned with via the PTS data, essentially timestaps, which
dicates the temporal relationship between audio and video in an MPEG
elementary stream.    If something bad happens (i.e. a frame drop) the
PVR-250 takes no notice of it; it will be indicated in the PTS data
and the player deals with keeping the sync locked together.

This isn't really wrong, and in fact seems like a good way to produce
perfectly synced audio (because the temporal position of each frame of
audio or video is indicated), but because most editing programs simply
disregard this and work on the raw video and audio streams, you get
'issues'  -- the lengths won't be exactly the same due to recording
flaws (like frame drops) and it will go out of sync.

The way to fix it is to have a program go through and readjust lengths
of the audio and video so that the raw streams sync properly -- by
dropping audio or video frames to make the actual video and audio
streams match the PTS data.

In Windows, you can do it with PVAStrumento (free) or VideoReDo (an
excellent MPEG cutter as well, not free, but not expensive).  I can
personally attest to VideoReDo -- it will actually work it out
automatically -- when it finishes saving a file (you can simply load a
file and save it) it presents you with a screen that lists any
adjustments it made.

I had previously believed there to be no program that does this for
Linux, but I stumbled upon something called vsplit while doing a bit
of research for this message.  I think it is in the package found
here:

http://www.dealdatabase.com/forum/showthread.php?t=36115&highlight=vsplit

If somebody could try this (someone who has sync problems) to see if
it actually works it could be big news.  Anyone care to give it a go?

-- 
Ian Trider
iantri at gmail.com