Alternative DivX profile for AutoGK bitrate spike control?

[snaveekima]

Hi, I have a Pinnacle Showcenter which struggles with higher bandwidth MPEG-4 content.
Using AutoGK with the DivX encoder and bitrate spike control option helps reduce the problem but not fix it, because the Showcenter is not compliant with the DivX Home Theater profile :(
Would it be possible to introduce a new option to AutoGK to specify alternative profile settings so that the bitrate can be brought into line with what the Showcenter can handle, or is there already a way round this? - apart from junking my Pinnacle box ;)
Thanks in advance.

[len0x]

Which DivX profile does Pinnacle support?

[snaveekima]

Hi. I don't think the Showcenter supports any DixX profile, unfortunately...
But, from what I have been able to understand about the DivX encoder there is the -vbv option that allows you to specify bitrate constraints independent of a predefined profile?
I was hoping to be able to specify -vbv parameters to AutoGK and have them passed through to the encoder - and then try to find values that give reliable playback on the Showcenter.
I'm a real newbie, so sorry if I've got the wrong idea here.

[len0x]

I see these parameters in the registry:
VBV Buffer Size (set to 3145728)
VBV Channel Bitrate (6951200)
VBV Occupancy (2359296)

I have no idea how they work (well only the first one may be). I don't think its very intuitive for newbies.

[snaveekima]

Thanks len0x. Reducing these registry values to:
VBV Buffer Size = 1000000
VBV Channel Bitrate = 3500000
VBV Occupancy = 750000
seems to fix my problem. (This is for an avi with an average bitrate of 3200000 which otherwise always stutters in a specific high-motion sequence). I'll do some further testing in the next week or so to try to figure out the highest values that the Showcenter can tolerate, but for now this looks good. Thanks again.

[musicnyman]

i tried this since i have pinnacle showcenter as well and in auto gk i used:

- ESS support
- bitrate spikes control
- set VBV channel bitrate to both 2K and 3K in registry

changed VBV channel bitrate to two different settings and avi file size is the same when using 100% quality. the avi is definitely spiking at 4K, so it's not working. it's using the old max channel bitrate.

is auto gk igonoring these registry settings and is forced somewhere in auto gk somehow? maybe the home theater profile is overriding the registry settings since i know they set the max bitrate to 4K in divx's home theater profile.

i know the max bitrate of the showcenter is about 3K, so i need to make sure the avi never spikes close to that.

thanks,

[len0x]

Quantizer-based pass encoding (single pass) does not respect VBV buffer. Use two passes instead.

[musicnyman]

doh! that's right, sorry... i'll try a 2-pass now.