OpenH264

OpenH264 is a codec library which supports H.264 encoding and decoding. It is suitable for use in real time applications such as WebRTC. See http://www.openh264.org/ for more details.

Encoder Features

Constrained Baseline Profile up to Level 5.2 (Max frame size is 36864 macro-blocks)
Arbitrary resolution, not constrained to multiples of 16x16
Rate control with adaptive quantization, or constant quantization
Slice options: 1 slice per frame, N slices per frame, N macroblocks per slice, or N bytes per slice
Multiple threads automatically used for multiple slices
Temporal scalability up to 4 layers in a dyadic hierarchy
Simulcast AVC up to 4 resolutions from a single input
Spatial simulcast up to 4 resolutions from a single input
Long Term Reference (LTR) frames
Memory Management Control Operation (MMCO)
Reference picture list modification
Single reference frame for inter prediction
Multiple reference frames when using LTR and/or 3-4 temporal layers
Periodic and on-demand Instantaneous Decoder Refresh (IDR) frame insertion
Dynamic changes to bit rate, frame rate, and resolution
Annex B byte stream output
YUV 4:2:0 planar input

Decoder Features

Constrained Baseline Profile up to Level 5.2 (Max frame size is 36864 macro-blocks)
Arbitrary resolution, not constrained to multiples of 16x16
Single thread for all slices
Long Term Reference (LTR) frames
Memory Management Control Operation (MMCO)
Reference picture list modification
Multiple reference frames when specified in Sequence Parameter Set (SPS)
Annex B byte stream input
YUV 4:2:0 planar output

OS Support

Windows 64-bit and 32-bit
Mac OS X 64-bit and 32-bit
Mac OS X ARM64
Linux 64-bit and 32-bit
Android 64-bit and 32-bit
iOS 64-bit and 32-bit
Windows Phone 32-bit

Architectures verified to be working

ppc64el

Processor Support

Intel x86 optionally with MMX/SSE (no AVX yet, help is welcome)
ARMv7 optionally with NEON, AArch64 optionally with NEON
Any architecture using C/C++ fallback functions

Building the Library

NASM needed to be installed for assembly code: workable version 2.10.06 or above, NASM can be downloaded from http://www.nasm.us/.
For Mac OSX 64-bit NASM needed to be below version 2.11.08 as NASM 2.11.08 will introduce error when using RIP-relative addresses in Mac OSX 64-bit

To build the arm assembly for Windows Phone, gas-preprocessor is required. It can be downloaded from git://git.libav.org/gas-preprocessor.git

For Android Builds

To build for android platform, You need to install android sdk and ndk. You also need to export **ANDROID_SDK**/tools to PATH. On Linux, this can be done by

export PATH=**ANDROID_SDK**/tools:$PATH

The codec and demo can be built by

make OS=android NDKROOT=**ANDROID_NDK** TARGET=**ANDROID_TARGET**

Valid **ANDROID_TARGET** can be found in **ANDROID_SDK**/platforms, such as android-12.
You can also set ARCH, NDKLEVEL according to your device and NDK version.
ARCH specifies the architecture of android device. Currently arm, arm64, x86 and x86_64 are supported, the default is arm. (mips and mips64 can also be used, but there's no specific optimization for those architectures.)
NDKLEVEL specifies android api level, the default is 12. Available possibilities can be found in **ANDROID_NDK**/platforms, such as android-21 (strip away the android- prefix).

By default these commands build for the armeabi-v7a ABI. To build for the other android
ABIs, add ARCH=arm64, ARCH=x86, ARCH=x86_64, ARCH=mips or ARCH=mips64.
To build for the older armeabi ABI (which has armv5te as baseline), add APP_ABI=armeabi (ARCH=arm is implicit).
To build for 64-bit ABI, such as arm64, explicitly set NDKLEVEL to 21 or higher.

For iOS Builds

You can build the libraries and demo applications using xcode project files
located in codec/build/iOS/dec and codec/build/iOS/enc.

You can also build the libraries (but not the demo applications) using the
make based build system from the command line. Build with

make OS=ios ARCH=**ARCH**

Valid values for **ARCH** are the normal iOS architecture names such as
armv7, armv7s, arm64, and i386 and x86_64 for the simulator.
Another settable iOS specific parameter
is SDK_MIN, specifying the minimum deployment target for the built library.
For other details on building using make on the command line, see
'For All Platforms' below.

For Linux Builds

You can build the libraries (but not the demo applications) using the
make based build system from the command line. Build with

make OS=linux ARCH=**ARCH**

You can set ARCH according to your linux device .
ARCH specifies the architecture of the device. Currently arm, arm64, x86 and x86_64 are supported

NOTICE:
If your computer is x86 architecture, for build the libnary which be used on arm/aarch64 machine, you may need to use cross-compiler, for example:
make OS=linux CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-g++ ARCH=arm64
or
make OS=linux CC=arm-linux-gnueabi-gcc CXX=arm-linux-gnueabi-g++ ARCH=arm

For Windows Builds

"make" must be installed. It is recommended to install the Cygwin and "make" must be selected to be included in the installation. After the installation, please add the Cygwin bin path to your PATH.

openh264/build/AutoBuildForWindows.bat is provided to help compile the libraries on Windows platform.
Usage of the .bat script:

`AutoBuildForWindows.bat Win32-Release-ASM` for x86 Release build  
`AutoBuildForWindows.bat Win64-Release-ASM` for x86_64 Release build  
`AutoBuildForWindows.bat ARM64-Release-ASM` for arm64 release build

for more usage, please refer to the .bat script help.

For All Platforms

Using make

From the main project directory:

make for automatically detecting architecture and building accordingly
make ARCH=i386 for x86 32-bit builds
make ARCH=x86_64 for x86 64-bit builds
make ARCH=arm64 for arm64 Mac 64-bit builds
make V=No for a silent build (not showing the actual compiler commands)
make DEBUGSYMBOLS=True for two libraries, one is normal libraries, another one is removed the debugging symbol table entries (those created by the -g option)

The command line programs h264enc and h264dec will appear in the main project directory.

A shell script to run the command-line apps is in testbin/CmdLineExample.sh

Usage information can be found in testbin/CmdLineReadMe

Using meson

Meson build definitions have been added, and are known to work on Linux
and Windows, for x86 and x86 64-bit.

See http://mesonbuild.com/Installing.html for instructions on how to
install meson, then:

meson builddir
ninja -C builddir

Run the tests with:

meson test -C builddir -v

Install with:

ninja -C builddir install

Using the Source

codec - encoder, decoder, console (test app), build (makefile, vcproj)
build - scripts for Makefile build system
test - GTest unittest files
testbin - autobuild scripts, test app config files
res - yuv and bitstream test files

Known Issues

See the issue tracker on https://github.com/cisco/openh264/issues

Encoder errors when resolution exceeds 3840x2160
Encoder errors when compressed frame size exceeds half uncompressed size
Decoder errors when compressed frame size exceeds 1MB
Encoder RC requires frame skipping to be enabled to hit the target bitrate,
if frame skipping is disabled the target bitrate may be exceeded

License

BSD, see LICENSE file for details.