I think it's been mentioned before that capture resolutions above
heightxheight (480x480 for ntsc) do little to improve the video
quality. So if you're above that try reducing to that resolution, then
comparing two recordings at the same (low) bitrate to see if the one
at 480x480 is really better. If it is, that should allow you to reduce
the bitrate a bit more.
On 10/9/05, Steven Ellis <[EMAIL PROTECTED]> wrote:
> Been trying to build up a series of profiles for doing different types
> of captures on my PVR-150. For example to get two or three 45 minute tv
> shows on a single DVD-R. Along the way i've noticed a couple of issues.
> In particular the average bitrate always seems to blow out a little bit
> high.
>
> Now for some encodes i've been using the following settings to get a HQ
> capture that I then re-encode. The aim is to get as clean an encode as
> possible so i've been playing with the data-rates.
>
> I have a shell script that tunes the bitrate to the level i'm after. The
> profies "two" and "three" were the attempts to get 2 or 3 shows on a
> single DVD5.
> -------
> #!/bin/bash
>
> ivtv_rate() {
>
> echo "Setting bitrate to $1"
> if [ "$1" == "dvd" ]; then
> ivtvctl -c bitrate_peak=8400000,bitrate=7400000,stream_type=14
> elif [ "$1" == "high" ]; then
> ivtvctl -c bitrate_peak=9600000,bitrate=8000000,stream_type=14
> elif [ "$1" == "max" ]; then
> ivtvctl -c bitrate_peak=30000000,bitrate=20000000,stream_type=0
> elif [ "$1" == "two" ]; then
> ivtvctl -c bitrate_peak=9000000,bitrate=5900000,stream_type=14
> elif [ "$1" == "three" ]; then
> ivtvctl -c bitrate_peak=9000000,bitrate=4000000,stream_type=14
> elif [ "$1" == "test" ]; then
> ivtvctl -c bitrate_peak=9000000,bitrate=7500000,stream_type=14
> fi
> }
>
> # High bitrate dvd profile
> ivtv_date high
>
> # Perform the capture
> cat /dev/video0 > out.mpg
>
> -----
>
> Now by accident I managed to set bitrate_peak=90000000, that is 90
> Million. This resulted in a very interesting file with bit rathes in the
> 18-22 Million mark.
> I thought this hardware was only capable ot a max of 16,000,000 which
> mean I was a little surprised at these values. At the moment my highest
> quality profile has a max of 30,000,000 with an aim for an average of
> 20,000,000.
>
> So can anyone tell me what the real capability of this card is, and also
> has anyone found some reasonable settings for capturing 90 or 135
> minutes to under 4.3Gb.
>
> Steve
>
> PS. Congrats on the 0.4 release.
>
> _______________________________________________
> ivtv-devel mailing list
> [email protected]
> http://ivtvdriver.org/mailman/listinfo/ivtv-devel
>
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