14 vp6, On2 vp6, 1 detailed description – Google Flix Engine Linux Reference Manual User Manual
Page 49: 2 defaults dependent on bits per pixel
5.14 VP6
43
5.14
VP6
5.14.1
Detailed Description
The VP6 (Flash 8) video codec.
Example Usage:
sc = Flix2_AddCodec(&codec, flix, FE2_CODEC_VP6);
// Use 450kbit
if(sc == ON2_OK)
sc = Flix2_CodecSetParam(codec, FE2_VP6_BITRATE, 450.0);
5.14.2
Defaults dependent on bits per pixel
Defaults for some encoder parameters are determined based on the bits per pixel, which is determined as
follows:
bitsperpixel =
FE2_VP6_BITRATE
∗ 1024
imagew ∗ imageh ∗ f ps
The current defaults are:
| <.03 | <.07 | <.12 | <.20 | >=.20
================================================================
FE2_VP6_MIN_Q
|
25
|
15
|
15
|
5
|
5
FE2_VP6_MAX_Q
|
62
|
56
|
50
|
40
|
32
FE2_VP6_SHARPNESS
|
1
|
1
|
5
|
7
|
7
FE2_VP6_NOISE_REDUCTION
|
3
|
0
|
0
|
0
|
0
FE2_VP6_TEMPORAL_RESAMPLING |
1
|
1
|
0
|
0
|
0
5.14.3
Notes on datarate control
Using the above defaults some material may fail to achieve the requested bitrate. This is highly material
dependent, but the result will be a clip with a reduced datarate. If you are intent on achieving a specific
datarate and find that your clips are missing it the following settings will help:
=====================================
FE2_VP6_MIN_Q
|
4
FE2_VP6_NOISE_REDUCTION
|
0
FE2_VP6_TEMPORAL_RESAMPLING
|
1
FE2_VP6_STREAM_PREBUFFER
|
5
FE2_VP6_STREAM_OPTIMAL_BUFFER |
5
Reasoning:
•
setting - The default minimum quantizer settings are an attempt to save bits for
harder sections. Unfortunately this means that on easy but high framerate and/or resolution clips the
desired quality cannot be achieved. The downside to this change is that more frames may be dropped
on harder sections.
•
setting - The usage of noise sensitivity set to non-0 is an attempt
to save bits by blurring the source. Sometimes the material is so easy that this attempt to save bits
may not only be unnecessary, it may actually hurt the visual quality by blurring. Again this may
cause more frames to be dropped in harder sections.
•
setting - This parameter should be enabled to guarantee
there are no extreme datarate spikes throughout the clip.
Generated on Tue Jul 20 17:39:03 2010 for Flix Engine Linux by Doxygen