Friday, July 15, 2005

Video capture with SageTV

Back in the spring, I switched over to using SageTV to do my daily captures using a Hauppauge card that captures in MPEG2 format. This saves me time since I don't have to re-encode the video, plus I'm capturing straight off-the-air rather then going via a S-VHS tape deck. The SageTV software also offers a lot of PVR functionality, including the ability to watch TV on another PC via the LAN.

The default capture mode that I have setup is a custom one created using the customization features that allow you to specify bitrates and formats. Overall, it's a VBR stream that is roughly 4Mbps average with peaks of up to 6Mbps and a 384Kbps MPEG1v2 stream. Since it's a real-time encoding using the Hauppauge board, it's not going to be super high quality VBR. But it's a bitrate that lets me put (3) TV episodes on a single disk. (See DVD Encoding Bitrates.)

Once I strip out commercials, each TV episode ends up around 43-44 minutes. So (3) of them weigh in at around 132 minutes on a single disc. That's adequate for displaying on older NTSC TVs and is a decent trade-off between size and quality. (That's subjective, so others will disagree.)

In the late summer, I plan on changing things around so that I'm only putting (2) episodes on a single disc. That will allow me to significantly up the bitrate. I estimate that I can use 6000 with a maximum of 8000 on the VBR settings (96min per DVD). I may even try 6500 with a maximum of 8000 (89min per DVD). Settling in at 6250 (93min) is probably the compromise setting.

Sage TV properties file (Sage.properties):

mmc/python2_encoding/DVD\ 4Mbps\
VBR=videobitrate\=4000000|
peakvideobitrate\=6000000|
vbr\=1|width\=720|height\=480|
audiobitrate\=384|outputstreamtype\=10|
audiosampling\=48000

mmc/python2_encoding/DVD\ 6Mbps\
VBR=videobitrate\=6000000|
peakvideobitrate\=8000000|
vbr\=1|width\=720|height\=480|
audiobitrate\=384|outputstreamtype\=10|
audiosampling\=48000

Note that the above are both supposed be a single line each in the property file, but I've broken them up over multiple lines here to be clearer.

Labels: 2005

posted by Wuphon's at 2:37 PM