KSC265codec(v2.6.1.3)
It should be noted that, the libraries used in our ios/andriod demos have expiration time.
ENCODER
Usage: command line examples
AppEncoder_x64 -i p_3840x2160_50.yuv -preset ultrafast/veryfast/slow/veryslow -latency offline -wdt 3840 -hgt 2160 -fr 50 -rc 1 -br 20000 -iper 128 -b test.265
AppEncoder_x64 -i p_3840x2160_50.yuv -preset ultrafast/veryfast/slow/veryslow -latency offline -wdt 3840 -hgt 2160 -fr 50 -rc 0 -qp 27 -iper 128 -b test.265
AppEncoder_x64 -i p_3840x2160_50.yuv -preset ultrafast/veryfast/slow/veryslow -latency offline -wdt 3840 -hgt 2160 -fr 50 -rc 3 -crf 24 -iper 128 -b test.265
Basic parameters:
-preset [preset_value],
which specifies the encoding speed by the character string [preset_value], among strings of "superfast", "veryfast", "fast", "medium", "slow", "veryslow" and "placebo".
-latency [latency_value],
which specifies the encoding latency by the character string [lactency_value], among strings of "zerolatency", "livestreaming", "offline". Note that, in the presets of ultrafast~veryfast, the latency under "livestreaming" and "offline" are the same.
-i [input_filename],
which specifies the address of the input YUV file in 4:2:0 sampling format by a character string [input_filename].
-wdt [width],
which specifies the image width of the input video by a positive integer value [width].
-hgt [height],
which specifies the image height of the input video by a positive integer value [height].
-fr [framerate],
which specifies the frame rate of the input video by a positive integer value [framerate].
-iper [intraperiod],
which specifies the maximum distances between consecutive I pictures by a positive integer value [intraperiod].
-rc [rctype],
which specifies the rate control type by the positive integer value [rctype] valuing among values 0(fixed qp), 1(cbr), 2(abr) and 3(crf). There are four cases:
- -br [bitrate] should be followed. If [rctype] equals to 1 or 2, a parameter -br [bitrate] should be followed and specifies the target encoding bit-rate by the positive value [bitrate] (kbps,kilo bit rate per second).
- -qp [qp_value] should be followed. If [rctype] equals to 0, a parameter -qp [qp_value] should be followed and specifies the target encoding quantization parameter by the positive value [qp_value] ranging from 0 to 51.
- -crf [crf_value] should be followed. If [rctype] equals to 3, a parameter -crf [crf_value] should be followed and specifies the target crf parameter by the positive value [crf_value] ranging from 0 to 51.
-b [stream_filename],
which specifies the address of the output stream file in HEVC/H.265 format by a character string [stream_filename]. Default: no stream is output.
Optional parameters:
-v or -V [version],
which is utilized to print the version and copyright of the encoder.
-psnr [psnrcalc],
which specifies psnr calculation method by a non-negative value [psnrcalc], and
- 0 (as a default value) means disabling psnr calculation,
- 1 means enabling psnr calculation and outputing the overall psnr result.
- 2 means enabling psnr calculation and outputing psnr info for each frame.
-o [reconstructYUV],
which specifies the address of the reconstrcuted yuv file in 4:2:0 format by a character string [reconstructYUV]. Default: no reconstructed YUV file is output.
-frms [frame_no],
which specifies the number of frames to be encoded for the input video by a positive integer value [frame_no]. Default: [frame_no] = -1, when all input frames are encoded.
-threads [thread_no],
which specifies the number of threads used to encode the input video by a non-negative value [thread_no]. Default: [thread_no] = 0, when all available threads can be utilized.
-bframes[value1], -vbv-maxrate [value2] , -vbv-bufsize[value3],
which specifies similar meanings as similar values defined in x264
DECODER
Usage: command line examples
AppDecoder_x64.exe -b test.265 -o test.yuv -threads 2
Basic parameters:
-v or -V [version]
which specifies the decoder version and copyright.
-b [bitstream],
which specifies input bit-stream file by a character string [bitstream].
Optional parameters:
-o [output],
which specifies the decoded yuv file name by a character string [output].
-threads [threadnum],
which specifies the number of threads used for decoding process by a non-negative value [threadnum]. Default: [threadnum] = 0, when all available threads can be utilized.
Performance of decoder
KSC265 decoder is compared with openHEVC in ffmpeg on ARM64@Andriod, ARM64@iOS and x86 platforms.
| decoding speed ( ksc265inFFmpeg / openHEVCInFFmpeg) |
iOS (ipad mini2) |
Andriod (VIVOxplay5a) |
PC (E5-2690 v3 @ 2.60GHz) |
|---|---|---|---|
| 1 thread | 2.90 | 2.85 | 2.11 |
| full threads | 2.69 | 2.99 | 3.89 |
On average, as above table shows, KSC265 decoder can achieve more than 2/2.5 times the speed of openHEVC in ffmpeg on x86/ARM, and details can be found in the excels for decoding performance. Moreover, as following table shows, the decoding speed of KSC265 now can well support the 1080p@25fps applications.
| decoding speed of ksc265inFFmpeg (in frames per second) |
iOS (ipad mini2) |
Andriod (VIVOxplay5a) |
PC (E5-2690 v3 @ 2.60GHz) |
|---|---|---|---|
| 1920x1080 @ 1thread | 32.06 | 32.94 | 177.19 |
| 1280x720 @ 1thread | 77.88 | 89.60 | 346.24 |
| 1920x1080 @ full threads | 51.13 | 90.44 | 939.25 |
| 1280x720 @ full threads | 120.20 | 187.16 | 1976.24 |
Performance of encoder
KSC265 encoder is firstly compared with X265-v2.4, X264 and vp9 on Win7@i7-4790@4threads using following parameters:
x264.exe -o out.264 BQSquare_416x240_60.yuv --input-res 416x240 --preset [superfast|veryfast|slow|placebo] --fps [framerate] --profile high --aq-mode 0 --no-psy --psnr --bitrate [btrNumber] --threads 1/0 --keyint [framerate * 10] --frames 1000000
AppEncoder_x64.exe -b out.265 -i BQSquare_416x240_60.yuv -preset [veryfast|slow|veryslow] -threads 1/0 -psnr 2 -rc 1 -br [btrNumber] -frms 1000000 -iper [framerate * 10]
x265.exe -o out.265 --input BQSquare_416x240_60.yuv --input-res 416x240 --preset [ultrafast|ultrafast|slow|veryslow] --fps [framerate] --aq-mode 0 --no-psy-rd --no-psy-rdoq --psnr --bitrate [btrNumber] --frame-threads [1|0] --no-wpp/--wpp --keyint [framerate * 10] --frames 1000000
vpxenc.exe --codec=vp9 --passes=1 --[rt|goog|best] --fps=[framerate]/1 --i420 --end-usage=vbr --target-bitrate=[btrNumber] --kf-max-dist=[framerate * 10] --cpu-used=8 --threads=[1|4] --psnr -w 416 -h 240 -o out.vp9 BQSquare_416x240_60.yuv --frame-parallel=0
Then on test sequences of JCTVC CLASS-A ~ CLASS-E, and one class of game videos@30fps, compared to x264(20161020), x265-v2.4 and vp9 in the speed form of encoded frames per second (fps), the average performance of KS265 can be summarized by the follows.
| KSC265 vs. X264 | KSC265 vs. X264 | KSC265 vs. X265 | KSC265 vs. X265 | KSC265 vs. vp9 | KSC265 vs. vp9 | |
|---|---|---|---|---|---|---|
| full-thread comparisons | Bitsaving @same quality | Speedup @same quality | Bitsaving @same quality | Speedup @same bitrate | Bitsaving @same quality | Speedup @same bitrate |
| RealTime+ | 43.7% | -5.4% | 26.0% | 212.6% | 30.5% | 147.9% |
| RealTime | 41.2% | 8.9% | 34.5% | 123.2% | 38.0% | 75.5% |
| Transcode | 36.2% | -5.1% | 23.7% | 199.1% | 32.6% | 179.0% |
| Best Ratio | 35.3% | 83.3% | 10.9% | 84.1% | 23.1% | 778.0% |
Secondly, then on test sequences of JCTVC CLASS-A ~ CLASS-E, and one class of showself videos@15fps, compared to x264(20161020), x265-v2.4 and vp9 in the speed form of encoded frames per second (fps), the average performance of KS265 on OPPOR9s@1thread and ipad min2 @1thread can be summarized by the follows.
| Andriod&iOS | Andriod | iOS | |
|---|---|---|---|
| full-thread comparisons | Bitsaving @same quality | Speedup @same quality | Speedup @same quality |
| superfast | 43.9% | -4.1% | 6.3% |
| veryfast | 43.4% | -2.2% | 1.2% |
| fast | 38.0% | 7.3% | 4.7% |
| medium | 36.2% | 4.8% | 7.1% |
The details are described in the excel document.