Thank you Robert!<br>
<br>
Can anyone add on to this? I'd like to use mytranscode or nuvexport. I
couldn't find a man page for either, but if someone will point me to
docs, I'll gladly read them.<br>
<br>
I'm trying to transcode 1080i and 720p down to 420p (852x420 pixels). I
would like to keep the bit rate as high as necessary to keep as close
to the original quality as possible but granted, throwing out 1/2 of
the information which won't display on my TVs native resolution anyway.<br>
<br>
Can anyone recommend a command line? I wanted to do some initial tests before setting up any automatic transcoding.<br>
<br>
Is MPEG4 considered to be higher quality or easier on decoding for
playback compared to MPEG2? I'm much less concerned about encoding
performance/time; playback quality and playback resource usage or my
primary concerns. If possible, it would be great if transcoded HTDV
(down to 420p) plays reasonably smoothly on a 1.6 MHz P4.<br>
<br><br><div><span class="gmail_quote">On 9/5/05, <b class="gmail_sendername">Robert Tsai</b> <<a href="mailto:rtsai1111@comcast.net">rtsai1111@comcast.net</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On Mon, Sep 05, 2005 at 02:00:42PM -0400, Brian McEntire wrote:<br>> I have an EDTV that doesn't go to full HDTV specs. It can display<br>> 480p, 720p, and 1080i formats, but it's native resolution is 852x420<br>> so any of the other formats are going to be downsampled.
<br>><br>> I'm having success recording HDTV over ATSC OTA with MythTV, but<br>> playback is choppy and I know it is because my computer is currently<br>> underpowered. I could upgrade, and probably will, but in the mean
<br>> time, and even after I upgrade, there is no reason to have HDTV<br>> shows at higher than 480p since they need to be downsampled to<br>> display on my TV anyway.<br>><br>> Can I save disk space and possibly improve playback performance with
<br>> transcoding? How to I manually and automatically set shows recorded<br>> in 1080i or 720p to be transcoded down to 480p?<br><br>I have a similar setup as you (record HDTV OTA for display on my<br>"HDTV" with only 856x480 resolution).
<br><br>Using the internal myth transcoder (mythtranscode):<br><br>In the setup menus, enter the "Recording Profiles", "Transcoders" and<br>set up the target resolution to be whatever you want it to be (
e.g.,<br>852x420) and some bitrate (I use 4400kbps with the bitrate scaled<br>against a 640x480 resolution, to end up with about 2GiB/hr) for the<br>"High Quality", "Medium Quality", and "Low Quality" transcoders. There
<br>are no predefined defaults; you have to set them up yourself.<br><br>In the "Default" recording profile, enable the "auto-transcode"<br>checkbox. This checkbox is for mixed systems where one might want to
<br>auto-transcode recordings captured from an HD-3000 (say), but not<br>re-encode recordings captured from a PVR-x50 card that has<br>hardware-assist.<br><br>Then in your recording schedules, enable auto-transcoding for that
<br>recording schedule.<br><br>Other people use nuvexport and "user jobs", but this requires more<br>configuration. I think the trade-off is that mythtranscode is<br>optimized for speed over quality, while nuvexport takes longer but
<br>produces higher-quality results for a given target filesize. But I<br>don't use nuvexport so I can't say from my personal experience.<br><br>--Rob<br><br><br>-----BEGIN PGP SIGNATURE-----<br>Version: GnuPG v1.4.1 (GNU/Linux)
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