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-DC-
Guest
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 Posted:
Thu Oct 28, 2004 11:05 pm Post subject:
Encoder settings (buffer, smoothness) |
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I'm encoding some TV streams at ~450Kbps (total) and have started looking at
the buffer and smoothness settings. I've used both 3s and 10s for the buffer
with no noticeable change in video quality. My key frame interval is 1s
because we're on a lossy wireless network and that setting helps to reduce
playback freezes after packet loss.
The smoothness setting has me curious though. If it's too high, the encoder
drops frames. The documentation says it's a trade off between detail and
smooth motion in the video. Does this setting ONLY control whether or not
the encoder drops frames in favor of more detail or is there more going on?
Will it also depend on the content being encoded (sports vs. talking head)?
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Zarax [Digital Media MVP]
Guest
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| Posted:
Fri Oct 29, 2004 11:26 am Post subject:
RE: Encoder settings (buffer, smoothness) |
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Basically, yes.
But there are a lot of factors that can influence smoothness and frame
dropping, like the source decoder, bitrate and encoding hardware.
"-DC-" wrote:
| Quote: | I'm encoding some TV streams at ~450Kbps (total) and have started looking at
the buffer and smoothness settings. I've used both 3s and 10s for the buffer
with no noticeable change in video quality. My key frame interval is 1s
because we're on a lossy wireless network and that setting helps to reduce
playback freezes after packet loss.
The smoothness setting has me curious though. If it's too high, the encoder
drops frames. The documentation says it's a trade off between detail and
smooth motion in the video. Does this setting ONLY control whether or not
the encoder drops frames in favor of more detail or is there more going on?
Will it also depend on the content being encoded (sports vs. talking head)?
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-DC-
Guest
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| Posted:
Fri Oct 29, 2004 6:44 pm Post subject:
RE: Encoder settings (buffer, smoothness) |
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"Zarax [Digital Media MVP]" wrote:
| Quote: | Basically, yes.
But there are a lot of factors that can influence smoothness and frame
dropping, like the source decoder, bitrate and encoding hardware.
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Understood. Fortunately I'm not dropping frames otherwise.
What about my buffer setting? Do you have a recommendation for a buffer
time with the settings I'm using (450Kbps, 1s KFI, high smoothness setting)?
I've read that 3-5s is generally fine, but have also seen numbers as high as
7-10s. I'm willing to go higher if it will provide better quality video at
this bitrate.
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Zarax [Digital Media MVP]
Guest
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| Posted:
Fri Oct 29, 2004 6:51 pm Post subject:
RE: Encoder settings (buffer, smoothness) |
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Basically, more buffer = higher quality.
If you are encoding for streaming environment then you should keep buffer
low for lower loading times.
Generally, 3-5 seconds are fine for most scenarios.
"-DC-" wrote:
| Quote: |
"Zarax [Digital Media MVP]" wrote:
Basically, yes.
But there are a lot of factors that can influence smoothness and frame
dropping, like the source decoder, bitrate and encoding hardware.
Understood. Fortunately I'm not dropping frames otherwise.
What about my buffer setting? Do you have a recommendation for a buffer
time with the settings I'm using (450Kbps, 1s KFI, high smoothness setting)?
I've read that 3-5s is generally fine, but have also seen numbers as high as
7-10s. I'm willing to go higher if it will provide better quality video at
this bitrate.
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-DC-
Guest
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| Posted:
Fri Oct 29, 2004 7:13 pm Post subject:
RE: Encoder settings (buffer, smoothness) |
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"Zarax [Digital Media MVP]" wrote:
| Quote: | Basically, more buffer = higher quality.
If you are encoding for streaming environment then you should keep buffer
low for lower loading times.
Generally, 3-5 seconds are fine for most scenarios.
|
Yes, that's identical to what the documentation says. I guess I was hoping
for a "magic number" for my settings, if there is one.
One other thing about smoothness--I've got four encoders with two different
types of capture cards (Osprey 220 and Osprey 560) and two different hardware
platforms. I've noticed that on the 220s (and slower hardware) I have to set
the smoothness level lower to keep from dropping frames than on the
higher-end hardware. If the smoothness setting along with bitrate determines
frame drops, why does it appear that the hardware also matters? None of the
encoders are overtaxed (CPU generally under 60%), so I'm a little puzzled as
to why I'm seeing a big difference (setting of 80 on one set and only 60 on
another to prevent frame drops.) |
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