x264 + Mediacoder + VBV + Maxrate = Bug

[Dark Shikari]

Originally Posted by thiagoprado

Security, time seek and bandwidth control.

It's a pay-per-view site.

Oh, in that case, of course it makes sense.

[thiagoprado]

I did a test video using the Fabio Sonnati's settings (the same I posted in the beginning).

The best I could find to stream video.

It's realy amazing the quality we can get with only 250Kbps.

Look at the video:

http://www.thiagoprado.com.br/teste.mp4

[Dark Shikari]

Originally Posted by thiagoprado

I did a test video using the Fabio Sonnati's settings (the same I posted in the beginning).

The best I could find to stream video.

It's realy amazing the quality we can get with only 250Kbps.

Look at the video:

http://www.thiagoprado.com.br/teste.mp4

You can still do better. Raise subme to 9 for starters (no matter what you do, this is worth it), and if you feel like wasting a ton of time, you can use --ref 16 --me tesa as well. Also, given how much your source used 5 bframes, you might benefit from raising --bframes a bit. If instead of wasting tons of time like the previous suggestions and want to save time without too much quality loss, drop trellis from 2 to 1.

x264 is good stuff

[thiagoprado]

Originally Posted by Dark Shikari

You can still do better. Raise subme to 9 for starters (no matter what you do, this is worth it), and if you feel like wasting a ton of time, you can use --ref 16 --me tesa as well. Also, given how much your source used 5 bframes, you might benefit from raising --bframes a bit. If instead of wasting tons of time like the previous suggestions and want to save time without too much quality loss, drop trellis from 2 to 1.

x264 is good stuff

My god! It's better. The image is sharper.

x264 is incredible

[Dark Shikari]

Also, you could try some psy-trellis; --psy-rd 1.0:0.2 will add sharpen things up (but tends to do so at the cost of slightly increased artifacting)

[thiagoprado]

Originally Posted by Dark Shikari

Also, you could try some psy-trellis; --psy-rd 1.0:0.2 will add sharpen things up (but tends to do so at the cost of slightly increased artifacting)

I will try

[thiagoprado]

Originally Posted by Dark Shikari

Also, you could try some psy-trellis; --psy-rd 1.0:0.2 will add sharpen things up (but tends to do so at the cost of slightly increased artifacting)

I did the test and the result is incredible but took a long time to encode.
Since my videos are basically one person talking at low motion scenes the 250Kbps are fine.
But in some motion scenes the image get blocky.

Is there any setting in x264 that can avoid blocky?

Thanks

[Dark Shikari]

Originally Posted by thiagoprado

I did the test and the result is incredible but took a long time to encode.
Since my videos are basically one person talking at low motion scenes the 250Kbps are fine.
But in some motion scenes the image get blocky.

Is there any setting in x264 that can avoid blocky?

What makes it blockier in higher motion scenes is the fact that you're limiting the bitrate using VBV--if those scenes could have higher peak bitrate, they'd get higher quality.

Also, using such a low deblock setting isn't helping either.

[thiagoprado]

Originally Posted by Dark Shikari

What makes it blockier in higher motion scenes is the fact that you're limiting the bitrate using VBV--if those scenes could have higher peak bitrate, they'd get higher quality.

Also, using such a low deblock setting isn't helping either.

Thanks

[Guest]

Originally Posted by Dark Shikari

Because the VBV algorithm is complicated and if it makes a mistake, it can result in the encoder thinking that that the VBV may underflow soon--when it actually isn't going to. It relies on predictions of frame size that have to be very accurate.

So if you can use a larger VBV buffer as I suggested (not maxrate), wouldn't this tend to mitigate the problem?

There's no reason to minimize the VBV buffer size. You just want it no bigger than the player's HW is providing.

[Dark Shikari]

Originally Posted by neuron2

So if you can use a larger VBV buffer as I suggested, wouldn't this tend to mitigate the problem?

Theoretically, but such bugs (depending on the cause) can be triggered merely by VBV being on regardless of actual VBV state.

Originally Posted by neuron2

There's no reason to minimize the VBV buffer size. You just want it no bigger than the player's HW is providing.

But he's not encoding for hardware--he's encoding for a software stream.

If he has a buffer of, for example, 10 seconds, that means you have to wait 10 seconds before you can tune in to the stream.

[Manao]

His gop is already 10 second long. I think he can afford a slightly longer VBV. Furthermore, in the OP, why --level 51 ?

[Dark Shikari]

Originally Posted by Manao

His gop is already 10 second long.

Ah you're right. In this case he could certainly get away with more VBV.

[thiagoprado]

Thanks, Guys

I increased the maxrate to 700 and the bufsize two 1400 (two seconds of 700Kbps peak).

Since I'm using a prebuffering of 5 seconds and the flash media server 3.5 now have the dynamic buffering, I think will be fine.

What is GOP?

[qbukhari]

Very impressive, Excellent work all of you

I am a mediacoder user too but a newbie I have learnt a lot from you guys. Hats Off !!!!

I am dyeing to know how to use these settings in mediacoder

# ".\codecs\x264.exe" "$(SourceFile)" --no-psnr --no-ssim --keyint 250 --min-keyint 25 --level 51 --vbv-maxrate 480 --vbv-bufsize 480 --me umh --merange 16 --no-fast-pskip --non-deterministic --subme 1 --ref 1 --partitions all --8x8dct --bframes 5 --direct auto --mixed-refs --trellis 2 --b-pyramid --weightb --deblock -2:-1 --bitrate $(VideoBitrate) --qcomp 0.6 --vbv-bufsize 480 --threads auto --stats "$(PassLogFile)" --pass 1 -o NUL

# ".\codecs\x264.exe" "$(SourceFile)" --no-psnr --no-ssim --keyint 250 --min-keyint 25 --level 51 --vbv-maxrate 480 --vbv-bufsize 480 --me umh --merange 16 --no-fast-pskip --non-deterministic --aq-mode 1 --aq-strength 1.0 --b-adapt 2 --ref 6 --subme 7 --psy-rd 1:0 --partitions all --8x8dct --bframes 5 --direct auto --mixed-refs --trellis 2 --b-pyramid --weightb --deblock -2:-1 --bitrate $(VideoBitrate) --qcomp 0.6 --vbv-bufsize 480 --threads auto --stats "$(PassLogFile)" --pass 2 -o "$(DestFile)"


how to enter these exact settings in my mediacoder ? a stupid question but please guide me.


Thanks

Bukhari
qbukhari@yahoo.com