Filesizes from GBPVR

[JackTheMan18]

A question about filesizes and bitrates:
1. I would like to record to disk something from TV, burn to DVD, and then watch on TV. Quality & resolution not required to be very high. I have NTSC, LeadTek PVR2000 hardware encoding card.

2. Originally, I thought (and the supplied software confirmed) that an MPEG2 file of 750MB for 30 minutes, should produce "sufficient" quality for this usage.

3. In GBPVR, I set up Custom1 to be:
Video resolution: NTSC 720*480
Variable
Bitrate: 2000
BitRate Peak: 2500
Audi Bit Rate:224
Audio Sample Rate: 48 Khz

4. This produced a file 2.5GB (almost twice what I had intended).

5. These are some key hints as to what kind of file was produced (output from the dvd burning process):

C:\Program Files\devnz\gbpvr>C:\utils\cPVAS.exe "G:\GB-PVR WorkArea\demux.ajb"
PVAStrumento 2.1.0.13
Parsing jobfile

ALERT> loglevel = 2
***
*** PVAStrumento 2.1.0.13
*** running at 02-02-2006 21:21
***
Stream info for
G:\GB-PVR WorkArea\The O.C\The O.C._20060202_20002100_original.mpg

Found 1 video stream.
Found 1 MPEG audio stream.

VIDEO #1
Resolution 720 x 480
Aspect ratio is 4:3
Frame rate 29.97 fps
Nominal bitrate 7000000 bps
First PTS: 00:00:00.333

MPEG AUDIO #1
MPEG1, Layer 2
stereo, sampled at 48.0 kHz.
Bitrate 384 kbps
Each frame contains 24.0 ms audio (1152 bytes)
First PTS: 00:00:00.333
(and this from dvdauthor/mplex)
INFO: [???] VIDEO STREAM: e0
INFO: [???] Frame width : 720
INFO: [???] Frame height : 480
INFO: [???] Aspect ratio : 4:3 display
INFO: [???] Picture rate : 29.970 frames/sec
INFO: [???] Bit rate : 4990000 bits/sec
INFO: [???] Vbv buffer size : 229376 bytes
INFO: [???] CSPF : 0
INFO: [???] Scanning for header info: Audio stream c0 (G:\GB-PVR WorkArea\tem
p.mpa)
INFO: [???] MPEG AUDIO STREAM: c0
INFO: [???] Audio version : 1.0
INFO: [???] Layer : 2
INFO: [???] CRC checksums : no
INFO: [???] Bit rate : 49152 bytes/sec (384 kbit/sec)
INFO: [???] Frequency : 48000 Hz
INFO: [???] Mode : 0 stereo
INFO: [???] Mode extension : 0
INFO: [???] Copyright bit : 0 no copyright
INFO: [???] Original/Copy : 0 copy
INFO: [???] Emphasis : 0 none

6. What values should I have under Custom1 to produce a good quality picture (from TV), but be under 750MB per 30 minutes?

Thanks in advance.
and, thanks to Reven for doing the MyVideos plugin.

[chud]

based on the info dump you provided, the mpeg file you recorded had a video bitrate of 7000kpbs and audio bitrate of 384kpbs. this should have given you a filesize of around 1.6GB.

for 2.5GB / 0.5hr would have to be around 11000kpbs video bitrate.

in any case, i would suggest that your recording did not use your custom setting. when you set up the recording, you are sure that you selected "custom 1" rather than "medium"?

a bitrate of 2000kpbs and audio of 224kpbs should yield about 500MB per 1/2 hour.

[replaytv]

I use half D1 with 352x480 which produce 530+MB file for 30 mins of video.

Dan L.

[jc8472]

I have a similar problem.

I tried to use set-top dvd recorder bitrates as a basis for my quality profiles, but they never seem to match my specs, even with the original hauppauge PVR-150 software. So my hypothesis is that the discrepancies lie in the hardware and drivers of my PVR-150. As an example, I set the low profile to 1.5 MBps to 1.7 Mbps, which should yield approx. 720 megabytes per hour. Instead, I recieved a 860 megabyte file size and remember I'm using the variable bitrate setting, which in turn, should be MUCH smaller than constant bitrate.

[chud]

you can use a tool like AVIcodec to view details about the audio and video bitrates of a video file.

the variable bitrate setting is not going to be smaller than a constant bitrate setting. you are specifying the target average bitrate and the peak bitrate that the encoder will use. in an ideal world this file should be the same size as a constant 1500kbps file, but be of higher quality because it has saved bits in low motion scenes and then used those extra bits in higher motion scenes. in reality the encoders don't usually hit their average bitrate targets, especially for a one pass encode. in my opinion, a vbr for a one pass encode is bordering on useless.

so, you *should* be encoding at effectively a constant 1500kbps, so the video portion of the avi should be 644MB/hr. you have to add in the audio, which for say 128kbps is another 55MB/hr, so we're up to a filesize of 700MB. add in some AVI overhead and 720MB is reasonable. your 860MB would suggest that you are encoding at an average rate even above your 1700 peak value...

[JackTheMan18]

So, Sub (and others in the know):
Does GBPVR really use the settings that the user specifies in config?
Can that be independantly verified?
Is there any other way to set the quality settings?
Is it dependant only on the config paramters, or in any way on the card itself?

[sub]

So, Sub (and others in the know):
Does GBPVR really use the settings that the user specifies in config?

Yes, it tries to, but there is a good chance it doesnt work with your Leadtek PVR2000. Many manufactures do it different ways, and I only test with Hauppauge and ATI cards, so can only confirm it on these cards. Your Leadtek probably just ignores my requests because it expects things to be done a different way again.