<br><div class="gmail_quote">On Wed, Nov 26, 2008 at 11:58 PM, Rod Smith <span dir="ltr"><<a href="mailto:mythtv@rodsbooks.com">mythtv@rodsbooks.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="Ih2E3d">On Wednesday 26 November 2008 05:01:15 pm Paulin wrote:<br>
><br>
> And I'm sorry if I'm not explaining things properly. A lot of this is very<br>
> new to me and I'm still trying to learn.<br>
><br>
> As for my Digital/Analog. Basically I have Comcast who is sending the<br>
> analog and digital over the line. I have two cards. The PVR250 recording<br>
> the analog channels from Comcast. Then I have a HVR1250 getting the<br>
> Comcast digital channels. I did realize they are all become MPEG files<br>
> and I would guess the digital is MPEG4 while the PVR is doing MPEG2 (but<br>
> that is a guess).<br>
<br>
</div>The PVR-250 definitely delivers MPEG-2 files. I don't use the HVR-1250, but<br>
based on the description on the MythTV wiki, it appears to be a simple<br>
digital (ATSC/QAM) capture card (with analog NTSC support in the hardware but<br>
not yet in the Linux drivers). As such, channels tuned with this card will<br>
also produce MPEG-2 files. Depending on the channels tuned and the MythTV<br>
settings for recording from the PVR-250, the digital channels could result in<br>
files that are smaller than, the same size as, or bigger than files from the<br>
PVR-250 (for recordings of identical length in time).<br>
<div class="Ih2E3d"><br>
> I figured the digital recordings are just bigger (bit rate/resolution)<br>
> which is accounting for the problem. So with that how can I adjust that.<br>
<br>
</div>You may be right, but unfortunately, there's no way to adjust the size of<br>
recordings from digital sources -- at least, not directly. A digital tuner<br>
card just takes the bitstream as delivered by the TV station or cable company<br>
and dumps that bitstream into a file. Any resolution or other size<br>
adjustments must be done after the fact. In MythTV, you'd do this with<br>
transcoding, which will of course take a lot of time and also convert from<br>
MPEG-2 to another format (probably MPEG-4).<br>
<br>
You can learn about your files' formats using the midentify command (see note<br>
below):<br>
<br>
$ midentify 4049_20081126195800.mpg<br>
<br>
You'll see a bunch of output. Pay attention to the following lines:<br>
<br>
ID_VIDEO_WIDTH=640<br>
ID_VIDEO_HEIGHT=480<br>
ID_VIDEO_FPS=29.970<br>
ID_VIDEO_CODEC=mpegpes<br>
<br>
The video width and height show the resolution of the recording, and the fps<br>
is the frames per second. You'll need to track down the files at a Linux<br>
command prompt to do this, of course. By default, MythTV names files using<br>
the tuner source and channel (4049 in this example), then the date and time<br>
(20081126195800 -- Nov. 26, 2008 at 19:58:00). Thus, you can easily find the<br>
right recording by searching on the date (and perhaps time):<br>
<br>
$ ls -lh *11261958*<br>
-rw-r--r-- 1 mythtv mythtv 2.4G 2008-11-26 21:03 4049_20081126195800.mpg<br>
-rw-rw-rw- 1 mythtv mythtv 123K 2008-11-26 21:03 4049_20081126195800.mpg.png<br>
<br>
Once you do the identification, you'll know how your PVR-250 is storing files<br>
(the values should match whatever you set up in MythTV) vs. what you're<br>
getting for the digital channels. If your digital channels are coming in at<br>
substantially higher resolution (say, 1280x720 or above), then you're<br>
recording HDTV. If you're watching this on an SD TV set, you might want to<br>
see if you can find equivalent digital SD channels on your cable lineup. If<br>
that fails, you may be able to tune such channels over the air (OTA) rather<br>
than via the cable system.<br>
<br>
A simpler way to identify your recordings, but one that provides less<br>
information, is to check the file size. You can do this from the MythTV<br>
interface. Depending on your settings, analog channels will probably clock in<br>
at between 0.5GB to 3GB per hour, but they could fall outside this range if<br>
you've set extreme bitrate values. On my system (using Cox cable in RI), HD<br>
digital channels consume about 6-8GB per hour. The only SD digital channels<br>
I'm getting right now are useless (TV guide and the like), but at one time I<br>
got an SD digital version of CBS. IIRC, it clocked in at about 1.5GB per<br>
hour. Your cable company can set its bitrates as it sees fit, so your figures<br>
may not exactly match these.<br>
<br>
A note about midentify: On my system, this is a script that calls mplayer with<br>
various options. If you don't have such a script, here's mine:<br>
<br>
#!/bin/sh<br>
#<br>
# This is a wrapper around the -identify functionality.<br>
# It is supposed to escape the output properly, so it can be easily<br>
# used in shellscripts by 'eval'ing the output of this script.<br>
#<br>
# Written by Tobias Diedrich <<a href="mailto:ranma%2Bmplayer@tdiedrich.de">ranma+mplayer@tdiedrich.de</a>><br>
# Licensed under GNU GPL.<br>
<br>
if [ -z "$1" ]; then<br>
echo "Usage: midentify <file> [<file> ...]"<br>
exit 1<br>
fi<br>
<br>
mplayer -vo null -ao null -frames 0 -identify "$@" 2>/dev/null |<br>
sed -ne '/^ID_/ {<br>
s/[]()|&;<>'"'"'\\!$" []/\\&/g;p<br>
}'<br>
<div class="Ih2E3d"><br>
> Second I know that the M10000 board has an MPEG decoder, so I'm surprised<br>
> the CPU is hit as much for playback. Or is it being hit for the data<br>
> transmission (streaming) that is causing the problem.<br>
<br>
</div>As I understand it, most video devices for Linux support, at best, only *HELP*<br>
for MPEG-2 decoding -- they can accelerate the process, but a good deal of<br>
number-crunching is still left to the CPU. Certainly this is true on my own<br>
system, which has an nVidia FX5200 card and Intel Celeron-D 3GHz CPU. From<br>
memory, CPU load is in the 5-10% range when playing back SD video, but in the<br>
50-70% range when playing back HD video. When misconfigured, I get 100% CPU<br>
use and stuttering playback when playing HD content. Thus, I'm skeptical that<br>
your 1GHz CPU could handle HD content.<br>
<br>
That said, I'm unfamiliar with your motherboard. A quick Google search<br>
suggests it's got a VIA chipset with integrated video and VIA's C3 CPU. I<br>
don't know what video drivers you're using (or should be using) or how well<br>
all this works under Linux. It's conceivable that your setup has better<br>
MPEG-2 support in the video drivers and hardware than nVidia's drivers<br>
provide with my FX5200 card, and/or that the C3 CPU does more work per CPU<br>
cycle than my Celeron-D. If so, you might be able to handle HD content, but I<br>
expect you'll be close to the edge at best.<br>
<div><div></div><div class="Wj3C7c"><br>
--<br>
Rod Smith</div></div></blockquote><div><br></div><div>Well I ran your script (Thank for that) and got the following on the two different recording types.</div><div><br></div><div>H1250 (Digital)</div><div><div>size: 4669085696</div>
<div><br></div><div>ID_VIDEO_ID=0</div><div>ID_AUDIO_ID=0</div><div>ID_FILENAME=2007_20081123200000.mpg</div><div>ID_DEMUXER=mpegps</div><div>ID_VIDEO_FORMAT=0x10000002</div><div>ID_VIDEO_BITRATE=6000000</div><div>ID_VIDEO_WIDTH=720</div>
<div>ID_VIDEO_HEIGHT=480</div><div>ID_VIDEO_FPS=29.970</div><div>ID_VIDEO_ASPECT=0.0000</div><div>ID_AUDIO_FORMAT=80</div><div>ID_AUDIO_BITRATE=0</div><div>ID_AUDIO_RATE=0</div><div>ID_AUDIO_NCH=0</div><div>ID_LENGTH=7197.39</div>
<div>ID_VIDEO_CODEC=mpegpes</div><div>ID_AUDIO_BITRATE=384000</div><div>ID_AUDIO_RATE=48000</div><div>ID_AUDIO_NCH=2</div><div>ID_AUDIO_CODEC=mad</div><div><br></div></div><div>H250 (Analog)</div><div>size: 2333061120</div>
<div><br></div><div><div>ID_VIDEO_ID=0</div><div>ID_AUDIO_ID=0</div><div>ID_FILENAME=2033_20081127070000.mpg</div><div>ID_DEMUXER=mpegps</div><div>ID_VIDEO_FORMAT=0x10000002</div><div>ID_VIDEO_BITRATE=6000000</div><div>ID_VIDEO_WIDTH=720</div>
<div>ID_VIDEO_HEIGHT=480</div><div>ID_VIDEO_FPS=29.970</div><div>ID_VIDEO_ASPECT=0.0000</div><div>ID_AUDIO_FORMAT=80</div><div>ID_AUDIO_BITRATE=0</div><div>ID_AUDIO_RATE=0</div><div>ID_AUDIO_NCH=0</div><div>ID_LENGTH=3595.59</div>
<div>ID_VIDEO_CODEC=mpegpes</div><div>ID_AUDIO_BITRATE=384000</div><div>ID_AUDIO_RATE=48000</div><div>ID_AUDIO_NCH=2</div><div>ID_AUDIO_CODEC=mad</div><div><br></div><div>Do any of the help?</div><div><br></div><div>Also I found out that MiniMyth (which is what I'm using on the VIA board) has XvMC built in support. I had it enabled. I also tried XvMC-VLD. So based on earlier discussion I believe (but I could defiantly be wrong) that the XvMC support isn't the problem.</div>
<div><br></div><div>Now I did have Deinterlace set to bobdeint. There are a host to choose from. Not sure what I should be using here. Any recommendations.</div><div><br></div><div>Thanks and I really appreciate all of the help. Hopefully this will start making sense soon.</div>
<div><br></div><div>steve</div></div><div></div></div>