Mailing List Archive

framerate question
just out of curiosity, what framerate does mythtv use for encoding? Is
there a way to change it? (I don't remember seeing an option in the
recording settings)

-Chris

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Re: framerate question [ In reply to ]
Thus spake Chris Petersen:
> just out of curiosity, what framerate does mythtv use for encoding? Is
> there a way to change it? (I don't remember seeing an option in the
> recording settings)

I would assume 30fps for PAL input sources, and 29.97... for NTSC
sources.

--
Nathan Poznick <poznick@conwaycorp.net>

Almost everything is easier to get into than out of...
Re: framerate question [ In reply to ]
Nathan Poznick wrote:

> I would assume 30fps for PAL input sources

25fps for PAL, I would think?

-S

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Re: framerate question [ In reply to ]
Thus spake Steve Brown:
> Nathan Poznick wrote:
>
> >I would assume 30fps for PAL input sources
>
> 25fps for PAL, I would think?

Sorry, my mistake. Framerates are a black art :-)
Let's see if I can get this right:

NTSC TV: 29.97
NTSC Film: 23.97 (played back at 29.97 via 3:2 pulldown)
PAL TV: 25
PAL Film: 24 (but typically played back at 25fps)

--
Nathan Poznick <poznick@conwaycorp.net>

"There are three kinds of death in this world. There's heart death,
there's brain death, and there's being off the network." -- Guy Almes
Re: framerate question [ In reply to ]
> NTSC TV: 29.97
> NTSC Film: 23.97 (played back at 29.97 via 3:2 pulldown)
> PAL TV: 25
> PAL Film: 24 (but typically played back at 25fps)

that looks right. But which does mythtv use?

-Chris

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Re: framerate question [ In reply to ]
Thus spake Chris Petersen:
> > NTSC TV: 29.97
> > NTSC Film: 23.97 (played back at 29.97 via 3:2 pulldown)
> > PAL TV: 25
> > PAL Film: 24 (but typically played back at 25fps)
>
> that looks right. But which does mythtv use?

Well, I would think it would use either NTSC TV or PAL TV framerates,
depending on the input source.

--
Nathan Poznick <poznick@conwaycorp.net>

"MASTER NINJA THEME SONG!!" -Joel. #322
Re: framerate question [ In reply to ]
Nathan Poznick wrote:

> Thus spake Chris Petersen:
>
>>>NTSC TV: 29.97
>>>NTSC Film: 23.97 (played back at 29.97 via 3:2 pulldown)
>>>PAL TV: 25
>>>PAL Film: 24 (but typically played back at 25fps)
>>
>>that looks right. But which does mythtv use?
>
>
> Well, I would think it would use either NTSC TV or PAL TV framerates,
> depending on the input source.
>

before this gets into a comedy routine...

it will use 29.97fps if you live in a country that uses NTSC which is
most of North America and South America and also Japan. Europe (and the
scandinavian countries?) use PAL which would be 25fps, THEREFORE, myth
will use 25fps in those countries...

in other words, mythtv is not converting the framerate from your
countries native cable system it is leaving it at whatever your cable
provider is pushing up the pipe.

is it clearer now?

Sean

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Re: framerate question [ In reply to ]
ok, now that we've established the framerates that myth encodes at, is
there any way to get AT this information?

I'm trying to use mplayers "edl" feature to take advantage of myth's
cutlist for direct encoding to s/vcd (mplayer will sput out a yuv with
all of the commercials removed based on data in the cutlist/edl), but
edl is in seconds, not frames, so I need a way to accurately turn the
cutlist into second-offsets.

-Chris

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Re: Re: framerate question [ In reply to ]
> ok, now that we've established the framerates that myth encodes at, is
> there any way to get AT this information?
>
> I'm trying to use mplayers "edl" feature to take advantage of myth's
> cutlist for direct encoding to s/vcd (mplayer will sput out a yuv with
> all of the commercials removed based on data in the cutlist/edl), but
> edl is in seconds, not frames, so I need a way to accurately turn the
> cutlist into second-offsets.
>
> -Chris

havent played with edl... but bits and pieces of the transcoding
features that are to come in myth 0.11 are aldready present... the
'mythtranscode' script for example... you can specify something like this:

$ mythtranscode -l -k -p Transcode -s 2003-07-12-19:00:00 -c 1056

just make sure that the recording settings in the Transcode profile are
as you want them (or identical to your source recording settings if you
dont care, since your converting it to svcd anyway)

do a 'mythtranscode --help' for details on what those command line
options are... that script will output the same file it used as source
(in my case "1056_20030712190000_20030712193000.nuv") but a new file
will be there with the same name but ending in .nuv.tmp that wont
contain the commercials. then you can use the same encoding process you
have been using for converting .nuvs to svcd.

i know that isnt the answer you were looking for but the results should
be the results that you desire (svcd's with the commercials removed
according to mythtv's cutlist). or you could just wait for these
transcoding features to be fully implemented into myth... which judging
by the flurry of activity in the dev and commits list probably isnt that
far off.

hope this helps. if you get it down to a science then maybe you could
write a nice little script for all of us to use? ;-)

Sean


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Re: Re: framerate question [ In reply to ]
I did eventually figure out how to get at the raw framerate data, thanks
to a little help from people able to actually read the C code (since I
had no idea where to look). I wrote a little perl routine to grab the
framerate from the NUV file header. pretty slick, actually.

> havent played with edl... but bits and pieces of the transcoding
> features that are to come in myth 0.11 are aldready present... the
> 'mythtranscode' script for example... you can specify something like this:
> $ mythtranscode -l -k -p Transcode -s 2003-07-12-19:00:00 -c 1056

So does it cut without transcoding yet?

-Chris

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