#Kvazaar An open-source HEVC encoder licensed under LGPLv2.1

Join channel #kvazaar_hevc in Freenode IRC network to contact us.

Kvazaar is not yet finished and does not implement all the features of HEVC. Compression performance will increase as we add more coding tools.

http://ultravideo.cs.tut.fi/#encoder for more information.

http://github.com/ultravideo/kvazaar/wiki/List-of-suggested-topics for a list of topics you might want to examine if you would like to do something bigger than a bug fix but don't know what yet.

##Using Kvazaar

Usage:
kvazaar -i <input> --input-res <width>x<height> -o <output>

Optional parameters:
      -n, --frames <integer>     : Number of frames to code [all]
      --seek <integer>           : First frame to code [0]
      --input-res <int>x<int>    : Input resolution (width x height) or
                  auto           : try to detect from file name [auto]
      --input-fps <number>       : Framerate of the input video [25.0]
      -q, --qp <integer>         : Quantization Parameter [32]
      -p, --period <integer>     : Period of intra pictures [0]
                                     0: only first picture is intra
                                     1: all pictures are intra
                                     2-N: every Nth picture is intra
          --vps-period <integer> : Specify how often the video parameter set is
                                   re-sent. [0]
                                     0: only send VPS with the first frame
                                     1: send VPS with every intra frame
                                     N: send VPS with every Nth intra frame
      -r, --ref <integer>        : Reference frames, range 1..15 [3]
          --no-deblock           : Disable deblocking filter
          --deblock <beta:tc>    : Deblocking filter parameters
                                   beta and tc range is -6..6 [0:0]
          --no-sao               : Disable sample adaptive offset
          --no-rdoq              : Disable RDO quantization
          --no-signhide          : Disable sign hiding in quantization
          --rd <integer>         : Rate-Distortion Optimization level [1]
                                     0: no RDO
                                     1: estimated RDO
                                     2: full RDO
          --full-intra-search    : Try all intra modes.
          --no-transform-skip    : Disable transform skip
          --aud                  : Use access unit delimiters
          --cqmfile <string>     : Custom Quantization Matrices from a file
          --debug <string>       : Output encoders reconstruction.
          --cpuid <integer>      : Disable runtime cpu optimizations with value 0.
          --me <string>          : Set integer motion estimation algorithm ["hexbs"]
                                     "hexbs": Hexagon Based Search (faster)
                                     "tz":    Test Zone Search (better quality)
          --subme <integer>      : Set fractional pixel motion estimation level [1].
                                     0: only integer motion estimation
                                     1: fractional pixel motion estimation enabled
          --pu-depth-inter <int>-<int> : Range for sizes of inter prediction units to try.
                                     0: 64x64, 1: 32x32, 2: 16x16, 3: 8x8
          --pu-depth-intra <int>-<int> : Range for sizes of intra prediction units to try.
                                     0: 64x64, 1: 32x32, 2: 16x16, 3: 8x8, 4: 4x4
          --no-info              : Don't add information about the encoder to settings.
          --gop <int>            : Length of Group of Pictures, must be 8 or 0 [0]
          --bipred               : Enable bi-prediction search
          --bitrate <integer>    : Target bitrate. [0]
                                     0: disable rate-control
                                     N: target N bits per second

  Video Usability Information:
          --sar <width:height>   : Specify Sample Aspect Ratio
          --overscan <string>    : Specify crop overscan setting ["undef"]
                                     - undef, show, crop
          --videoformat <string> : Specify video format ["undef"]
                                     - component, pal, ntsc, secam, mac, undef
          --range <string>       : Specify color range ["tv"]
                                     - tv, pc
          --colorprim <string>   : Specify color primaries ["undef"]
                                     - undef, bt709, bt470m, bt470bg,
                                       smpte170m, smpte240m, film, bt2020
          --transfer <string>    : Specify transfer characteristics ["undef"]
                                     - undef, bt709, bt470m, bt470bg,
                                       smpte170m, smpte240m, linear, log100,
                                       log316, iec61966-2-4, bt1361e,
                                       iec61966-2-1, bt2020-10, bt2020-12
          --colormatrix <string> : Specify color matrix setting ["undef"]
                                     - undef, bt709, fcc, bt470bg, smpte170m,
                                       smpte240m, GBR, YCgCo, bt2020nc, bt2020c
          --chromaloc <integer>  : Specify chroma sample location (0 to 5) [0]

  Parallel processing:
          --threads <integer>    : Maximum number of threads to use.
                                   Disable threads if set to 0.

  Tiles:
          --tiles-width-split <string>|u<int> : 
                                   Specifies a comma separated list of pixel
                                   positions of tiles columns separation coordinates.
                                   Can also be u followed by and a single int n,
                                   in which case it produces columns of uniform width.
          --tiles-height-split <string>|u<int> : 
                                   Specifies a comma separated list of pixel
                                   positions of tiles rows separation coordinates.
                                   Can also be u followed by and a single int n,
                                   in which case it produces rows of uniform height.

  Wpp:
          --wpp                  : Enable wavefront parallel processing
          --owf <integer>|auto   : Number of parallel frames to process. 0 to disable.

  Slices:
          --slice-addresses <string>|u<int>: 
                                   Specifies a comma separated list of LCU
                                   positions in tile scan order of tile separations.
                                   Can also be u followed by and a single int n,
                                   in which case it produces uniform slice length.

  Deprecated parameters: (might be removed at some point)
     Use --input-res:
       -w, --width               : Width of input in pixels
       -h, --height              : Height of input in pixels

Example: kvazaar -i <INPUT_YUV> --input-res x -o <OUTPUT.BIN> -n <NUMBER_OF_FRAMES> -q

eg. kvazaar -i BQMall_832x480_60.yuv --input-res 832x480 -o out.bin -n 600 -q 32

The only accepted input format so far is 8-bit YUV 4:2:0.

##Compiling Kvazaar

If you have trouble regarding compiling the source code, please make an issue about in Github. Others might encounter the same problem and there is probably much to improve in the build process. We want to make this as simple as possible.

###Required libraries

• For Visual Studio pthreads-w32 library is required. Platforms with native posix thread support don't need anything.
  • The project file expects the library to be in ../pthreads.2/ relative to kvazaar. You can just extract the pre-built library there.
  • The executable needs pthreadVC2.dll to be present. Either install it somewhere or ship it with the executable.

###Visual Studio 2010

• VS2010 and older does not have support for some of the c99 features that we use. Please use VS2013 or newer or GCC (MinGW) to compile on windows.

###Visual Studio 2013

• project files included
• requires external vsyasm.exe in %PATH%
  • run rundll32 sysdm.cpl,EditEnvironmentVariables and add PATH to user variables

###GCC

• Simple Makefile included in src/
• Yasm is expected to be in PATH

###OS X

• The program should compile and work on OS X but you might need a newer version of GCC than what comes with the platform.

###Other

• There is a scons SConstruct file that should work on both Windows and Linux.
• Contact us for support or write an issue in Github

##Contributing to Kvazaar

###For version control we try to follow these conventions:

• Master branch always produces a working bitstream (can be decoded with HM).
• Commits for new features and major changes/fixes put to a sensibly named feature branch first and later merged to the master branch.
• Always merge the feature branch to the master branch, not the other way around, with fast-forwarding disabled if necessary. We have found that this differentiates between working and unfinished versions nicely.
• Every commit should at least compile. Producing a working bitstream is nice as well, but not always possible. Features may be temporarily disabled to produce a working bitstream, but remember to re-enbable them before merging to master.

###Testing:

• We do not have a proper testing framework yet. We test mainly by decoding the bitstream with HM and checking that the result matches the encoders own reconstruction.
• You should at least test that HM decodes a bitstream file made with your changes without throwing checksum errors. If your changes shouldn't alter the bitstream, you should check that they don't.
• We would like to have a suite of automatic tests that also check for BD-rate increase and speed decrease in addition to checking that the bitstream is valid. As of yet there is no such suite.

###Unit tests:

• There are some unit tests located in the tests directory. We would like to have more.

• The Visual Studio project links the unit tests against the actual .lib file used by the encoder. There is no Makefile as of yet.

• The unit tests use "greatest" unit testing framework. It is included as a submodule, but getting it requires the following commands to be run in the root directory of kvazaar:

    git submodule init
    git submodule update
  

###Code style:

We try to follow the following conventions:

• C99 without features not supported by Visual Studio 2013 (VLAs).
• // comments allowed and encouraged.
• Follow overall conventions already established in the code.
• Indent by 2 spaces. (no tabs)
• { on the same line for control logic and on the next line for functions
• Reference and deference next to the variable name.
• Variable names in lowered characters with words divided by underscore.
• Maximum line length 79 characters when possible.
• Functions only used inside the module shouldn't be defined in the module header. They can be defined in the beginning of the .c file if necessary.

###Resources for HEVC bitstream features:

• A good first resource for HEVC bitstream is JCTVC-N1002 High Efficiency Video Coding (HEVC) Test Model 12 (HM12) Encoder Description
• Many good articles regarding specific parts of HEVC can be found on IEEE Transactions on Circuits and Systems for Video Technology, Combined issue on High Efficiency Video Coding (HEVC) Standards and Research
• The specification tends to follow the reference implementation, not the other way around, so check HM if the specification is unclear.