[mythtv-users] Transcoding Advice

[Steven Adeff]

On Thu, Jan 6, 2011 at 2:32 PM, Christopher Meredith
<chmeredith at gmail.com> wrote:
> On Thu, Jan 6, 2011 at 12:50 PM, Steven Adeff <adeffs.mythtv at gmail.com>
> wrote:
>>
>> On Tue, Jan 4, 2011 at 10:40 PM, E. Westbrook
>> <mythtv-users at westbrook.com> wrote:
>> > On Tue, Jan 4, 2011 at 15:05, Steven Adeff <adeffs.mythtv at gmail.com>
>> > wrote:
>> >>
>> >> I'm actually trying to find a good way to do this with being able to
>> >> cut out the commercials.
>> >
>> > If mencoder is a workable alternative for you, apparently someone once
>> > had
>> > some luck creating EDL (edit decision list) files from MythTV cutlist
>> > data
>> > pulled out of the database.  I haven't tried the approach, or the script
>> > (and would probably use the perl bindings instead, if I did), but did
>> > find
>> > it interesting.
>> >
>> > http://www.mythtv.org/pipermail/mythtv-users/2005-July/094886.html
>> >
>> > $0.02,
>> > EW
>>
>> I'd be happy just to find something that will let me cut the
>> commercials out with a 1:1 transcoding, like how Myth's internal was
>> when it worked.
>>
>> The problem I have now is that for whatever reason ProjectX no longer
>> lets me choose cut points by frame, and I get a constant audio shift
>> when trying to use avidemux, a shift value that varies from mpeg to
>> mpeg, and I can't seem to find a consistent way to know what that
>> shift is.
>>
>
> A little while ago I tried everything I could think of to get workable
> lossless HD-PVR transcoding. I found that the only way to avoid audio shift
> using avidemux was to ensure that the recording had 6-channel AC3 audio. I
> included a function in my user job that would check if the source file had
> 6-channel AC# and if not, convert it. Although hackish, this resulted in
> fairly consistent success IIRC. That said, the avidemux method still isn't
> frame accurate and I ended up abandoning it. Now, I have mt recording
> profile set to use the HD-PVR in CBR mode its highest setting, then
> transcode to MPEG2. Although lossy, this makes the recording compatible with
> the existing myth tools, including mythtranscode for frame-accurate
> commercial cutting. I have a little 26" 720p display and from the couch, I
> can't see any difference between the original and MPEG2-transcoded files. If
> you're interested, drop me a line and I'll send you my scripts.

I believe avidemux now has a "transcode" method that will preserve the
original except where re-encoding is needed for cut frames. It seems
to work quite well, if only I could figure out the audio sync issue...

-- 
Steve
http://www.mythtv.org/wiki/User:Steveadeff
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