[mythtv] Ticket #12303: mythtranscode destroys audio
raymond at wagnerrp.com
Tue Nov 18 05:36:43 UTC 2014
On 11/17/2014 7:18 AM, Dan Wilga wrote:
> On 11/15/14 6:48 AM, Raymond Wagner wrote:
>> On 11/14/2014 7:25 AM, John Pilkington wrote:
>>> On 14/11/14 12:26, MythTV" wrote:
>>>> #12303: mythtranscode destroys audio
>>>> Would it help to have the two files?
>>>> 34M before.mpg
>>>> 76M after.nuv
>>> It's unlikely to do any harm to put them in a drop-box somewhere...
>>> ... but isn't this supposed to be about compression?
>> If you want to actually perform recompression of your files, instead
>> of simply performing a lossless cut of MPEG2 recordings, you
>> shouldn't use mythtranscode. You seem to be recompressing to RTJPEG
>> for some reason, but even properly configured, mythtranscode is
>> limited to MPEG4ASP, which is only a modest increase in
>> compressibility over MPEG2, and you're stuck in a NUV container.
> I have to disagree with the statement regarding MPEG4 compression
> using mythtranscode. When I record OTA using my HDHR on a 1080i
> channel, I end up with a result that is anywhere from 7.2 to 9.8
> Gb/hour. After going through mythtranscode to MPEG4, it ends up about
> 3.2 Gb. Is this optimal in terms of size/quality compared to other
> codecs? Certainly not. But it's a roughly 60% savings in disk space
> that requires much less CPU to achieve compared to better codecs like
> H.264. The tradeoff between CPU usage and disk savings is pretty good,
Clipping commercials and remuxing to a more efficient container would
bring those to 4-5GB in just a few minutes of work. Regardless, using
mythtranscode to actually transcode means you're stuck with a
Nuppelvideo file and practically no support outside of MythTV. Even if
you continue to use ASP, you're still better off using something other
than mythtranscode to accomplish that.
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