[mythtv-users] minimize the amount of disk space used by recordings
tmetro+mythtv-users at gmail.com
Wed Apr 18 02:24:56 UTC 2007
Michael T. Dean wrote:
> Tom Metro wrote:
>> ...1 Mbps Xvid encoded HD video is about 350 MB,
>> ...1 Mbps MythTV MPEG4 encoded SD video runs nearly 1.3 GB.
> By definition, a 1Mbps video--using /any/ CODEC--is just under 430MiB.
> So, if the video in that transcoded stream you've created is really
> 430MiB, you're wasting a /huge/ amount of space on audio. :)
I guess I'd have to examine the .nuv file to know (are there tools that
will report such data on .nuv files?), but the recording profile used an
MP3 audio codec with 32K sampling and quality of 7. I'm not sure what
average bitrate that'll correspond to.
> In reality, though, you just missed a very important checkbox in your
> transcoding (or recording) profile:
> Scale bitrate for frame size
> If set, the MPEG4 bitrate will be used for 640x480. If other
> resolutions are used, the bitrate will be scaled appropriately.
It was set, and my default MythTV record resolution is 350 x 480 (with
some older recordings at 480 x 480), so I guess bitrate numbers between
the two formats aren't directly comparable.
I disabled that setting, and transcoded a couple of shows. The log says
the transcodes completed, but oddly the pre- and post-transcode file
sizes hardly changed (1.29 -> 1.29 GB in one case, 2.12 -> 2.22 GB in
another). Something must be off...
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