How to get best possible picture quality

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How to get best possible picture quality

Postby evgtun » Tue Aug 04, 2009 11:09 pm

I have video quality at "Lossless quality, crazy bitrate" and bandwith limit set at 100Mbit.
I was wondering if picture quality of mkv files is downgraded when it is streamed to PS3.

Thanks
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Re: How to get best possible picture quality

Postby helal » Wed Aug 05, 2009 12:57 pm

no idea
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Re: How to get best possible picture quality

Postby meskibob » Wed Aug 05, 2009 1:57 pm

evgtun wrote:I have video quality at "Lossless quality, crazy bitrate" and bandwith limit set at 100Mbit.
I was wondering if picture quality of mkv files is downgraded when it is streamed to PS3.

Thanks

Lossless = shouldn't have video quality degradation
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Re: How to get best possible picture quality

Postby evgtun » Thu Aug 06, 2009 8:20 am

meskibob wrote:
evgtun wrote:I have video quality at "Lossless quality, crazy bitrate" and bandwith limit set at 100Mbit.
I was wondering if picture quality of mkv files is downgraded when it is streamed to PS3.

Thanks

Lossless = shouldn't have video quality degradation


But why is there a bandwith limitation? When i limit my bandwith something must be sacrificed.
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Re: How to get best possible picture quality

Postby Heathcliff » Thu Aug 06, 2009 12:02 pm

evgtun wrote:But why is there a bandwith limitation? When i limit my bandwith something must be sacrificed.


Well, the bandwidth probably isn't limited, because even an HD movie in lossless mpeg will probably never exceed 100 Mbit/s. I happened to test an mkv-file yesterday with lossless encoding and this particular movie never exceeded 20 Mbit/s. However, action-movies will probably have a higher bitrate. When the movie does exceed 100 Mbit MEncoder will degrade the picture quality a little bit so that it stays within that bandwidth. But you probalby won't notice that. Also, your rendering device will probably have a buffer too, at least for a few seconds of movie. So when you don't limit your bandwidth and the bitrate of the movie peaks a bit over 100 Mbit/s you might not even notice that either, because your rendering device will play from the buffer and the buffer will catch up after the peak. If you set the bandwidth limit to 20 Mbit/s for example, and you play the movie, the network traffic may exceed 20 Mbit/s if your network has more bandwidth, because your rendering device will always try to fill up its buffers. So it may use more network bandwidth that it needs to play, when its decoding buffer is drying up. Note that the maximum bandwidth setting is only obeyed when transcoding is used. If the media server is just streaming or remuxing, then the max bandwidth is not obeyed. The max bandwidth only affects the max decoding speed, not necessarily the network bandwidth. However those speeds are related.

Hope that explains it a bit for you.

René
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Re: How to get best possible picture quality

Postby meskibob » Thu Aug 06, 2009 12:42 pm

The bandwidth limitation is there to balance CPU load and network throughput. The less bandwidth available, the more the CPU has to work to do real-time transcoding. It shouldn't have anything to do with the video quality. If a file does outperform your [edit]system[/edit] (can happen on intense scenes), the quality won't degrade, the file will simply stutter.
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Re: How to get best possible picture quality

Postby Heathcliff » Thu Aug 06, 2009 12:50 pm

meskibob wrote:The bandwidth limitation is there to balance CPU load and network throughput. The less bandwidth available, the more the CPU has to work to do real-time transcoding.

Yes

meskibob wrote:It shouldn't have anything to do with the video quality.

I'm no expert. But if you set your max bandwidth according to your network, the encoder will degrade video quality to meet your bandwidth restrictions, right? Or am I missing the point?

meskibob wrote:If a file does outperform your network (can happen on intense scenes), the quality won't degrade, the file will simply stutter.

If the encoder settings are not configured to have a max bandwidth according to your network, it will indeed start to stutter when the bandwidth exceeds your network.

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Re: How to get best possible picture quality

Postby meskibob » Thu Aug 06, 2009 1:06 pm

Heathcliff wrote:I'm no expert. But if you set your max bandwidth according to your network, the encoder will degrade video quality to meet your bandwidth restrictions, right? Or am I missing the point?
From my understanding the video quality is pretty much all handled through the keyint, vqscale, and vqmin parameters. The max bandwidth setting is there to limit the output bitrate, not the video quality (not really a direct relationship in this case).
Heathcliff wrote:
meskibob wrote:If a file does outperform your network (can happen on intense scenes), the quality won't degrade, the file will simply stutter.

If the encoder settings are not configured to have a max bandwidth according to your network, it will indeed start to stutter when the bandwidth exceeds your network.
Sorry, should have phrased that better, although the quality not degrading is still correct. The file will stutter because your system can not keep up with trying to package the intense scene in a constrained bitrate, not because MEncoder let the bitrate above your specified max bandwidth and above the capabilities of your network.
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Re: How to get best possible picture quality

Postby evgtun » Thu Aug 06, 2009 7:41 pm

If i have bandwith limit set to 0 then 1080p movies stutters sometimes when lots of action on the screen. the bitrate goes up to 200mbps sometimes. so i set limit too 100mbit but i cant seem to see the difference in picture quality. Maybe my 37" tv is to small to see the difference.
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Re: How to get best possible picture quality

Postby meskibob » Thu Aug 06, 2009 7:55 pm

evgtun wrote:If i have bandwith limit set to 0 then 1080p movies stutters sometimes when lots of action on the screen. the bitrate goes up to 200mbps sometimes. so i set limit too 100mbit but i cant seem to see the difference in picture quality.

a) That coincides with my statements above 8-)
b) Isn't that a good thing? ;)
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