[mythtv-users] Transcode advice

Ted Roche tedroche at gmail.com
Thu Oct 16 18:55:50 UTC 2008

Here's my setup:

Backend: AMD 3500+, 1.5 Gb RAM, 80 Gb HDD for videos
pcHDTV-5500 [3], currently configured for analog capture
Running MythDora 5 [4]

Source: Comcast analog cable, there are some QAM-256 signals for OTA channels

Front end: Koolu: Geode, 512 Mb RAM 80Gb HDD, VGA out via Geode LX,
running Ubuntu Hardy (8.04)

Monitor: Samsung 23" 720p TV model LC-R238WA

I understand the front end is pretty low-powered; that's the idea.
Most of our TV is analog and a lot of what we watch are 70s and 80s
re-runs probably running off VHS tape, so we're not terribly concerned
about quality. Our usage is quite low, a few shows a week, and
power-savings (and what hardware's on hand) wins over super-quality.

The Koolu has an AMD Geode chipset that has hardware-assisted MPEG-2
decoding. Running from the .nuvs produced from the back-end, video was
unwatchably choppy.

I used nuvexport [1] and Transcode to convert one of the videos from
.nuv to DivX and manually copied it to the F/E hdd, just to eliminate
network problems, too, and the video was snappy (Sound was
high-pitched and buzzy, but I suspect that's another problem.). Here's
my questions, finally:

1. The nuvexport noted the original video was 480x480 rjpg - is that
the right format for the pcHDTV-5500 to be capturing, or is there a
better format. If so, where do I specify it?

2. If I'm going in the right direction, I'd like to set up the MythTV
B/E to automatically transcode the recorded shows, but I find the
transcode settings hard to decipher, even reviewing the docs at [2].
Can someone explain, or point to another reference on how to set up a
transcode (if that's really what I should be doing) to convert these
files automatically?

3. The Geode LX is capable of a range of resolutions, up to 1280 x
720, down to 1024x768, 800x600, 640x480. With the most recent Geode LX
drivers and the fixed DDC communication, the video/monitor combination
offers about a dozen settings. Is there an optimal setting to get the
best compromise between highest resolution (considering the source
materials) and the best performance?

4. Currently, I'm just capturing analog video, but I anticipate adding
the ability to capture the cable's digital QAM-256 signals for the OTA
channels. Is there anything different I should be doing in capturing
or transcoding them?

5. The audio after the transcode was high-pitched, tinny and buzzy. I
think I'd see a post about that recently in the list. Anyone got a

Thanks in advance for any help!

[1] http://www.mythtv.org/wiki/index.php/Nuvexport
[2] http://www.mythtv.org/wiki/index.php/Transcode
[3] http://www.pchdtv.com/hd_5500.html
[4] http://mythdora.com/

Ted Roche

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