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1 : chl 120 EXAMPLES for usage of xvid_stat:
2 :    
3 :     **********************************************************************************
4 :    
5 :     EXAMPLE 1
6 :    
7 :     $ xvid_stat < cactus.pgm
8 :    
9 :     This calls xvid_stat with standard parameters for the 3 frames from the
10 :     cactus file from examples directory.
11 :    
12 :     Output should look similar to this:
13 :    
14 :     Frame 0: intra 1, enctime = 4.7 ms length= 12470 bytes dectime = 4.2 ms PSNR 39.93
15 :     Frame 1: intra 0, enctime = 6.9 ms length= 1369 bytes dectime = 1.8 ms PSNR 40.40
16 :     Frame 2: intra 0, enctime = 6.6 ms length= 3354 bytes dectime = 2.3 ms PSNR 42.03
17 :     Avg. Q6 br 0900 (0.43 bpp) size 5731 (1146 kbps / 0.54 bpp) enc: 164.7 fps, dec: 362.0 fps
18 :     PSNR P(2): 41.22 ( 40.40 , 42.03 ; 0.4698 ) I(1): 39.93 ( 39.93 , 39.93 ; 0.0000 )
19 :    
20 :    
21 :     The lines in detail:
22 :     For every input frame one line is printed containing the data:
23 :    
24 :     Frame the frame number, starting with 0
25 :     intra if the frame was encoded as I-frame (1) or P-frame (0),
26 :     when B-frames are supported, they will get a value of 2 here.
27 :    
28 :     enctime time for encoding this frame, in milliseconds (1/1000th of a second)
29 :     length length of the MPEG-4 bitstream generated from this frame (in bytes)
30 :     dectime time for decoding
31 :     PSNR picture signal to noice ratio (a measurement of quality, higher is better)
32 :    
33 :     then in the end, two status lines are printed, these can be used, e.g. for automatic
34 :     quality tests:
35 :    
36 :     Avg. indicated that we are now talking about average values
37 :     Q6 quality parameter that was used (so here it was quality level 6)
38 :     br 0900 bitrate mode was used with a bitrate of 900kbps the other possibility is "q"
39 :     instead of "br", see another example
40 :     size 5731 average size of an encoded frame
41 :     1146 kbps "real" bitrate that was achieved, it may differ from the bitrate given to the
42 :     codec as a parameter, because this is real life
43 :     0.54 bpp number of bit per pixel for the encoding, useful when comparing videos of
44 :     different size
45 :     enc: 164.7 fps speed of encoding in frames per second
46 :     dec: 362.0 fps speed of decoding in frames per second
47 :    
48 :     ******************************************************************************************
49 :    
50 :     EXAMPLE 2
51 :    
52 :     $ xvid_stat 0 0 6 900 25 < cactus.pgm
53 :    
54 :     This does exactly the same as above, but parameters
55 :     quality = 6,
56 :     bitrate = 900
57 :     framerate = 25
58 :     are provided instead of using default value. Output should be the same as in last example.
59 :     Note that first and second parameter are 0, indicating that a PGM file should be read
60 :     (which has a header that includes X and Y dimensions).
61 :    
62 :     ******************************************************************************************
63 :    
64 :     $ xvid_stat 0 0 1 8 < cactus.pgm
65 :    
66 :     Output:
67 :    
68 :     Frame 0: intra 1, enctime = 4.1 ms length= 8420 bytes dectime = 3.4 ms PSNR 36.36
69 :     Frame 1: intra 0, enctime = 3.0 ms length= 659 bytes dectime = 1.5 ms PSNR 36.36
70 :     Frame 2: intra 0, enctime = 2.7 ms length= 595 bytes dectime = 1.5 ms PSNR 36.43
71 :     Avg. Q1 q 0008 (0.00 bpp) size 3224 ( 644 kbps / 0.31 bpp)enc: 304.3 fps, dec: 467.1 fps
72 :     PSNR P(2): 36.40 ( 36.36 , 36.43 ; 0.0210 ) I(1): 36.36 ( 36.36 , 36.36 ; 0.0000 )
73 :    
74 :     This time, quality 1 is used, so output values are a little different. Since the fourth parameter
75 :     (here 8) is smaller than 32, it is not considered as a bitrate value, but as a fixed quantizer.
76 :     So in the "Avg." line there is a
77 :    
78 :     q 0008 meaning "fixed quantizer mode" with quantizer 8.
79 :    
80 :    
81 :     ******************************************************************************************
82 :    
83 :     $ xvid_stat 176 144 5 112 < foreman.qcif
84 :    
85 :     This switches xvid_stat to RAW instead of PGM mode. The input is expected to be
86 :     images of dimensions 176*144 in raw YUV 4:2:0 format. (So every image is exactly
87 :     38016 = 176*144 + 88*72 + 88*72 bytes in size). Some reference streams are in
88 :     this format. Note that you MUST give correct dimensions, because they cannot be
89 :     detected from the YUV material.
90 :     Apart from this, the example uses quality 5 and a bitrate of 112 kbps with video speed
91 :     of 30 frames per second (this is not encoding or decoding speed, but the speed at
92 :     which the video would be played. This value is only important for ratecontrol...)
93 :    
94 :    

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