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Examples : |
Examples : |
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1) bzip2 -dc cactus.pgm.bz2 | ./xvid_encraw -t 1 |
1) bzip2 -dc cactus.pgm.bz2 | ./xvid_encraw -type 1 |
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This command decompress cactus.pgm.bz2 and pipe the pgm file to |
This command decompress cactus.pgm.bz2 and pipe the pgm file to |
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xvid_encraw that will compress it to mpeg4 format. No mp4 stream |
xvid_encraw that will compress it to mpeg4 format. No mp4 stream |
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output is written to disc. |
output is written to disk. |
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2) ./xvid_encraw -t 1 -i cactus.pgm -m 1 |
2) ./xvid_encraw -type 1 -i cactus.pgm -save |
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Compress cactus.pgm frames into mpeg4 stream, and then writes a m4v |
Compress cactus.pgm frames into mpeg4 stream, and then writes a |
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file per encoded frame. |
m4v file per encoded frame. |
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3) ./xvid_encraw -t 1 -i cactus.pgm -m 1 -o my_xvid_example.m4v |
3) ./xvid_encraw -type 1 -i cactus.pgm -o my_xvid_example.m4v -stats |
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Same thing as above but saves all raw m4v data to a unique file. |
Same thing as above but saves all raw m4v data to a singlefile, |
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and displays yuv-plane psnr statistics to stdout. |
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4) ./xvid_encraw -t 1 -i cactus.pgm -m 1 -mt 1 -o my_xvid_example.mp4u |
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Same as above but encapsulates the m4v stream into the mp4u file |
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format. |
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** xvid_decraw.c |
** xvid_decraw.c |
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---------------------------------------------------------------------- |
---------------------------------------------------------------------- |
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Examples : |
Examples : |
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1) ./xvid_decraw -w 352 -h 240 -t 1 -i stream.mp4u -d 1 |
1) ./xvid_decraw -i stream.m4v -d |
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This command decodes a mp4u file (-t 1 option) from stream.mp4u and |
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writes all decoded frames to single PGM files (framexxxxx.pgm). |
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2) cat stream.m4v | ./xvid_decraw -w 352 -h 240 |
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This one reads a m4v file from standard input and outputs just |
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decoding statistics. |
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NB :-w and -h parameters are mandatory as XviD lacks a "discover |
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width and height" from m4v stream. This feature will be added at |
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a later time, so for now we must use these options. |
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* xvid_stat.c |
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---------------------------------------------------------------------- |
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This last example is a kind of xvid_dec/encraw merged program, it |
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encodes PGM or YUV files and decode the resulting mp4 stream to |
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measure both encoding and decoded times as well as PSNR. |
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Type "xvid_stat -help" to have all options' description. |
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Examples: |
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1) ./xvid_stat < cactus.pgm |
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This calls xvid_stat with standard parameters for the 3 frames from |
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the cactus file from examples directory. |
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Output should look similar to this: |
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Frame 0: intra 1, enctime = 4.7 ms length= 12470 bytes dectime = 4.2 ms PSNR 39.93 |
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Frame 1: intra 0, enctime = 6.9 ms length= 1369 bytes dectime = 1.8 ms PSNR 40.40 |
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Frame 2: intra 0, enctime = 6.6 ms length= 3354 bytes dectime = 2.3 ms PSNR 42.03 |
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Avg. Q6 br 0900 (0.43 bpp) size 5731 (1146 kbps / 0.54 bpp) enc: 164.7 fps, dec: 362.0 fps |
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PSNR P(2): 41.22 ( 40.40 , 42.03 ; 0.4698 ) I(1): 39.93 ( 39.93 , 39.93 ; 0.0000 ) |
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The lines in detail: |
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For every input frame one line is printed containing the data: |
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Frame the frame number, starting with 0 |
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intra if the frame was encoded as I-frame (1) or P-frame (0), when |
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B-frames are supported, they will get a value of 2 |
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here. enctime time for encoding this frame, in milliseconds |
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(1/1000th of a second) |
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length length of the MPEG-4 bitstream generated from this frame (in |
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bytes) |
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dectime time for decoding |
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PSNR picture signal to noice ratio (a measurement of quality, |
This command decodes a m4v file from stream.m4v and saves all |
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higher is better) |
decoder output frames to individual PGM files (framexxxxx.pgm). |
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Then in the end, two status lines are printed, these can be used, |
2) cat stream.m4v | ./xvid_decraw |
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e.g. for automatic quality tests: |
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Avg. indicated that we are now talking about average values |
This examples decodes a m4v stream from standard input, but does |
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save any decoded frames. |
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Q6 quality parameter that was used (so here it was quality |
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level 6) |
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br 0900 bitrate mode was used with a bitrate of 900kbps the other |
** xvid_bench.c |
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possibility is "q" instead of "br", see another example. |
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size 5731 average size of an encoded frame |
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1146 kbps "real" bitrate that was achieved, it may differ from the |
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bitrate given to the codec as a parameter, because this is |
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real life |
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0.54 bpp number of bit per pixel for the encoding, useful when |
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comparing videos of different size |
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enc: 164.7 fps speed of encoding in frames per second |
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dec: 362.0 fps speed of decoding in frames per second |
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2) ./xvid_stat -q 6 -b 900 -f 25 -i cactus.pgm |
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This does exactly the same as above, but parameters are provided |
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instead of using default value. Output should be the same as in last |
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example. Note that first and second parameter are 0, indicating |
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that a PGM file should be read (which has a header that includes X |
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and Y dimensions). |
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3) ./xvid_stat -t 1 -q 1 -quant 8 -i cactus.pgm |
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Output: |
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Frame 0: intra 1, enctime = 4.1 ms length= 8420 bytes dectime = 3.4 ms PSNR 36.36 |
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Frame 1: intra 0, enctime = 3.0 ms length= 659 bytes dectime = 1.5 ms PSNR 36.36 |
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Frame 2: intra 0, enctime = 2.7 ms length= 595 bytes dectime = 1.5 ms PSNR 36.43 |
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Avg. Q1 q 0008 (0.00 bpp) size 3224 ( 644 kbps / 0.31 bpp)enc: 304.3 fps, dec: 467.1 fps |
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PSNR P(2): 36.40 ( 36.36 , 36.43 ; 0.0210 ) I(1): 36.36 ( 36.36 , 36.36 ; 0.0000 ) |
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This time, quality 1 is used, so output values are a little |
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different. Since the fourth parameter (here 8) is smaller than 32, |
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it is not considered as a bitrate value, but as a fixed quantizer. |
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So in the "Avg." line there is a : |
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q 0008 meaning "fixed quantizer mode" with quantizer 8. |
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4) ./xvid_stat -w 176 -h 144 -q 5 -b 112 -i foreman.qcif |
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This switches xvid_stat to RAW instead of PGM mode. The input is |
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expected to be images of dimensions 176*144 in raw YUV 4:2:0 |
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format. (So every image is exactly 38016 = 176*144 + 88*72 + 88*72 |
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bytes in size). Some reference streams are in this format. Note |
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that you MUST give correct dimensions, because they cannot be |
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detected from the YUV material. Apart from this, the example uses |
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quality 5 and a bitrate of 112 kbps with video speed of 30 frames |
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per second (this is not encoding or decoding speed, but the speed at |
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which the video would be played. This value is only important for |
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ratecontrol...) |
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** MP4U Format |
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| 70 |
---------------------------------------------------------------------- |
---------------------------------------------------------------------- |
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- Header : |
This is a tool to conduct unit testing and profiling of the signal |
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processing functions used internally within libxvidcore. |
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+-----+-----+-----+-----+ |
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| M | P | 4 | U | |
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+-----+-----+-----+-----+ |
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|1byte|1byte|1byte|1byte| |
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+-----+-----+-----+-----+ |
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- Encoded frame |
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+------+----------------------- ... --+ |
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| size | ... Frame data ... | |
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+------+----------------------- ... --+ |
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|4bytes| 'size' bytes | |
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+------+----------------------- ... --+ |
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+ size is written in big endian format |
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+ frame data is m4v raw data generated by XviD core. |
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- File format |
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Header + x*Encoded frame |
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Patch