[mythtv-users] Optimum encoding for remote mythtv

Johnny Lee johnny at fishcounts.com
Mon May 10 13:07:14 EDT 2004


> On Mon, 2004-05-10 at 10:57, Boyd II, Willy wrote:
>
>> Not sure if this has been addressed yet, as I just caught this reply and
>> I'm not using threaded messaging.... but:
>>
>> You won't help your download times be leaving the bitrate the same.  Th
>> The only thing that will change by reducing the resolution, is slightly
>> better quality on a TV, because you're encoding less pixels, but more
>> information about them.  Make sense?  I can't think of a better laymen's
>> way to explain but someone else probably can.
>>
>> So I would suggest doing both:  reduce resolution to, say, 352x480, and
>> drop the resolution a bit until you find it just acceptable to watch.
>> i.e. 2000kbps might look really bad at 720x480, but not quite so bad at
>> 352x480.
>
> While this is most definately true, I might suggest what someone else
> mentioned.
>
> Record the programs at 720x480 at 8/12/16000 per second. Make sure you
> get a good record of the program. The idea here is not to transfer the
> file but get as a high of quality digital stream that you can handle to
> start with.
>
> Next, use mencoder, or the transcode options of mythtv. transcode it
> over to mpeg4 maybe with ogg sound or somesuch. as far as the video, you
> can then reduce it to something smaller and limit the bitrate down to 1k
> or 1.5k. An mpeg4 stream will have the same quality as a meg 4 stream at
> the same resolution and a much lower bit rate. The downside is that the
> transcode will take some time to complete if you dont ahve a beefy cpu.
> The upside is your file transfers wil lbe MUCH faster for the same
> quality of video.
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I have a similar setup.

P4 2.53ghz
512MB 1066mhz Rambus
120GB 7200 8MB Hard drive
Nvidia Geforce MX 440 64MB w/ TV out (primary)
Winfast Deluxe w/ dbx stereo (NTSC Analog cable)
Fedora Core 1
xv decoding on
kernel deinterlace on

My configuration is using:

Default recording rate(i primarily use this 99% of the time)
Video - MPEG4 5000bps 640x480 (proper 4x3 ratio)
Audio - 41k

Live TV rate
Video - MPEG4 6000bps 640x480 (proper 4x3 ratio)
Audio - 41k


With this setup I can do pretty much anything and don't really have any
issues with frame loss. I can record a show and be watching a prerecorded
show at the same time. Sometimes I even transcode a show while one is
recording and haven't noticed any issues.

On a side note. Does anyone know how I can convert this to mpeg2 for SVCD?
I use avidemux2 and it works properly for DVD but when I try to do SVCD
for some reason the audio doesn't work on the exported mpeg file...

Johnny Lee


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