Parent Directory
|
Revision Log
Revision 392 - (view) (download)
1 : | Isibaar | 3 | xvid vfw help |
2 : | 20/jan/02 | ||
3 : | |||
4 : | *** rate control *** | ||
5 : | |||
6 : | xvid offers a number of different rate control modes | ||
7 : | |||
8 : | - 1pass-cbr: constant-bitrate | ||
9 : | use the bitrate slider to select the desired bitrate; refer to 'cbr constants' for advanced options. note: we actually use an average-bitrate algorithm, so the instaneous bitrate will fluxuate. | ||
10 : | |||
11 : | - 1pass-quality | ||
12 : | use the quality slider to select a desired quality percentile. the quality% is then used to calculate an average-quantizer. | ||
13 : | |||
14 : | - 1pass-quantizer | ||
15 : | force the codec to use a fixed quantizer for all frames. valid range: [1,31]. | ||
16 : | |||
17 : | - 2pass | ||
18 : | a detailed explaination of 2pass can be found here: http://www.research.ibm.com/journal/rd/434/westerink.html | ||
19 : | our implementation of two pass encoding requires three steps | ||
20 : | 1) 1stpass: collect compression statisics to a stats file. | ||
21 : | 2) process the stats using gordian knot, xihprom, etc. | ||
22 : | 3) 2ndpass: compress the video using both the original 1stpass stats file, and the normalized stats file. | ||
23 : | |||
24 : | |||
25 : | *** encoder tuning *** | ||
26 : | |||
27 : | - max keyframe interval | ||
28 : | the maximum interval between keyframes. | ||
29 : | |||
30 : | - motion search precision | ||
31 : | controls the speed/quality of the motion search algorithm. range [0,6]. | ||
32 : | lower values are faster but reduce compressibility. | ||
33 : | higher values are slower but increase compressibility. | ||
34 : | |||
35 : | - quantization type | ||
36 : | quantization is the process of removing detail. there are two types: | ||
37 : | h.263: used by divx4.x and h263 encoders. | ||
38 : | mpeg: used by the microsoft mpeg-4 encoder, mpeg-1/2. | ||
39 : | |||
40 : | mpeg quantization gives sharper looking images, but can introduce grain/noise. while h.263 gives softer looking images, removes noise (but sometimes too much) and is slightly faster. | ||
41 : | |||
42 : | |||
43 : | *** cbr constants *** | ||
44 : | |||
45 : | these apply only to 1pass-cbr mode. | ||
46 : | |||
47 : | - average peroid | ||
48 : | the number of frames over which the average bitrate is maintained. | ||
49 : | |||
50 : | - reaction peroid | ||
51 : | (?) the number of frames inwhich we react to sudden change in bitrate. | ||
52 : | |||
53 : | - up/down ratio | ||
54 : | (?) a percentile representing how fast/much we react. | ||
55 : | |||
56 : | |||
57 : | *** debug *** | ||
58 : | |||
59 : | - min/max quantizer. | ||
60 : | lets you limit the flexibility of the encoder. | ||
61 : | a minquant=1 can sometimes cause problems with 1pass-cbr and 2pass. | ||
62 : | |||
63 : | - luminance masking | ||
64 : | enabled per-macroblock quantizer decision. very experimental | ||
65 : | |||
66 : | - discard encoded bitstream on 1st-pass | ||
67 : | by default xvid discards the compressed bitstream during the the 1st pass of a two pass encoding session. example: in windows you end up with an empty .avi file. if this box is unchecked the bitstream is kept. | ||
68 : | note: the 1st compressed bitstream can large. | ||
69 : | |||
70 : | this can be used to perform a 'fast 2pass' encoding. | ||
71 : | 1) perform 1st pass encoding of your source material with discard unchecked. | ||
72 : | 2) process the stats file | ||
73 : | 3) open the bitstream created in the first pass, and perform the 2nd pass on it. | ||
74 : | note: there is some quality loss. judge it for yourself. | ||
75 : | |||
76 : | - perform dummy 2nd-pass | ||
77 : | this can be used to check the accuracy of your stats file processor/calculator. it instructs xvid to create a dummy/junk bitstream exactly to the size described in the processed stats file. | ||
78 : | |||
79 : | *** cpu *** | ||
80 : | |||
81 : | provides auto/manual control over cpu-feature optimizations. | ||
82 : | |||
83 : | |||
84 : | *** about *** | ||
85 : | |||
86 : | build timestamp, etc. |
No admin address has been configured | ViewVC Help |
Powered by ViewVC 1.0.4 |