RasPi GPU Transcoder version 1.0

Introduction

gputranscoder is an application that utilizes the Rasperry Pi GPU for transcoding transport stream media files.

Design Decisions

• In order to encode/decode video using the GPU on the RasPi the appropriate api to use is OpenMAX IL layer.
• Hence gputranscoder has dependency to OMX IL libraries.
• ilclient library is a helper library that isolates some complexity of the OpenMax API and also handles multithreaded event management needed for OpenMax applications
• gputranscoder uses ilclient library which is the first dependency.
• For demuxing/remuxing first choice was OMX.Broadcom.read_media component. But this proved to be in effective since GPU does not have access to filesystem and even if it did, it is not clear whether the component supports TS files.
• Final decision was to use libavformat from ffmpeg for demuxing/muxing support. The final big chunk of dependencies come from this decision.
• gputranscoder only encodes video stream since there is no hardware audio encoding support on RasPi yet.

Basic Usage

gputranscoder needs an input_filename and output_filename to operate at minimum.

Important!!!: Make sure your output filename ends with a “ts” extension. The output container is guessed by the filename.

Extra config arguments are optional. Default values are 2Mbit for bitrate, false for deinterlacing , info for log level and size is copied from the input stream.

Basic usage is printed by the app itself as follows

./gputranscoder 
Usage: gputranscoder [-s WxH] [-b target_bitrate] [-d] [-L log_level]  <infile> <outfile>

    -s size        Resize output.  'size'  format is WidthxHeight (Not Supported Yet)
    -b bitrate    Target bitrate in bits/second. Low bitrates may result in frame drops
    -d        Deinterlace (Not supported yet)
    -L        Debug Level: 1:error 2:warn 3:info 4:debug

Output container is guessed based on outfile name.  Use '.ts' for transport stream output.

Input file must contain one of MPEG 2 or H.264 video.
Make sure You have installed necessary codecs in your RasPi

Note that size and deinterlacing options are not enabled in the first binary

Library Dependencies

There are three major chunk of dependencies 1. OpenMAX api related dependencies. If these are not installed yet, you must build them on the Raspberry Pi under /opt/ folder

  libGLESv2.so => /opt/vc/lib/libGLESv2.so (0x76378000)
  libEGL.so => /opt/vc/lib/libEGL.so (0x7634f000)
    libopenmaxil.so => /opt/vc/lib/libopenmaxil.so (0x76340000)
    libbcm_host.so => /opt/vc/lib/libbcm_host.so (0x76322000)
    libvcos.so => /opt/vc/lib/libvcos.so (0x76310000)
    libvchiq_arm.so => /opt/vc/lib/libvchiq_arm.so (0x76302000)

2. FFmpeg related dependencies. For demuxing main lib is libavformat which depends on libavcodec which in turn brings in many dependencies. Although none of the soft codecs here are needed, the default ffmpeg on RasPi repository has them enabled so they will all be listed as a dependency.

If you do not have ffmpeg installed you must install it. sudo apt-get install ffmpeg. For future development, you will also need the development versions of libavutil libavformat and libavcodec

  /usr/lib/arm-linux-gnueabihf/libcofi_rpi.so (0x76fc9000)
    libavformat.so.54 => /usr/lib/arm-linux-gnueabihf/neon/vfp/libavformat.so.54 (0x76ec3000)
    libavcodec.so.54 => /usr/lib/arm-linux-gnueabihf/neon/vfp/libavcodec.so.54 (0x763be000)
    libavutil.so.52 => /usr/lib/arm-linux-gnueabihf/neon/vfp/libavutil.so.52 (0x76395000)
    librtmp.so.0 => /usr/lib/arm-linux-gnueabihf/librtmp.so.0 (0x76113000)
    libxvidcore.so.4 => /usr/lib/arm-linux-gnueabihf/libxvidcore.so.4 (0x75ee9000)
    libx264.so.130 => /usr/lib/arm-linux-gnueabihf/neon/vfp/libx264.so.130 (0x75d85000)
    libvpx.so.1 => /usr/lib/arm-linux-gnueabihf/libvpx.so.1 (0x75d2b000)
    libvorbisenc.so.2 => /usr/lib/arm-linux-gnueabihf/libvorbisenc.so.2 (0x75bbd000)
    libvorbis.so.0 => /usr/lib/arm-linux-gnueabihf/libvorbis.so.0 (0x75b8d000)
    libvo-amrwbenc.so.0 => /usr/lib/arm-linux-gnueabihf/libvo-amrwbenc.so.0 (0x75b6d000)
    libvo-aacenc.so.0 => /usr/lib/arm-linux-gnueabihf/libvo-aacenc.so.0 (0x75b4a000)
    libtheoraenc.so.1 => /usr/lib/arm-linux-gnueabihf/libtheoraenc.so.1 (0x75b09000)
    libtheoradec.so.1 => /usr/lib/arm-linux-gnueabihf/libtheoradec.so.1 (0x75aea000)
    libspeex.so.1 => /usr/lib/arm-linux-gnueabihf/libspeex.so.1 (0x75acc000)
    libschroedinger-1.0.so.0 => /usr/lib/arm-linux-gnueabihf/libschroedinger-1.0.so.0 (0x75a14000)
    libopus.so.0 => /usr/lib/libopus.so.0 (0x759d0000)
    libopenjpeg.so.2 => /usr/lib/arm-linux-gnueabihf/libopenjpeg.so.2 (0x759ae000)
    libopencore-amrwb.so.0 => /usr/lib/arm-linux-gnueabihf/libopencore-amrwb.so.0 (0x75994000)
    libopencore-amrnb.so.0 => /usr/lib/arm-linux-gnueabihf/libopencore-amrnb.so.0 (0x75969000)
    libmp3lame.so.0 => /usr/lib/arm-linux-gnueabihf/libmp3lame.so.0 (0x758ec000)
    libgsm.so.1 => /usr/lib/arm-linux-gnueabihf/libgsm.so.1 (0x758da000)
    libva.so.1 => /usr/lib/arm-linux-gnueabihf/libva.so.1 (0x758be000)
    libdl.so.2 => /lib/arm-linux-gnueabihf/libdl.so.2 (0x758b2000)
    libgcrypt.so.11 => /lib/arm-linux-gnueabihf/libgcrypt.so.11 (0x75832000)
    libtasn1.so.3 => /usr/lib/arm-linux-gnueabihf/libtasn1.so.3 (0x7581c000)
    libp11-kit.so.0 => /usr/lib/arm-linux-gnueabihf/libp11-kit.so.0 (0x75805000)
    libogg.so.0 => /usr/lib/arm-linux-gnueabihf/libogg.so.0 (0x757f8000)
    liborc-0.4.so.0 => /usr/lib/arm-linux-gnueabihf/liborc-0.4.so.0 (0x7577d000)
    libgpg-error.so.0 => /lib/arm-linux-gnueabihf/libgpg-error.so.0 (0x75772000)

3. Arm libc and generic libraries only listed as information

  libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0x760f5000)
    libgnutls.so.26 => /usr/lib/arm-linux-gnueabihf/libgnutls.so.26 (0x7603b000)
    libbz2.so.1.0 => /lib/arm-linux-gnueabihf/libbz2.so.1.0 (0x76021000)
    libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0x75ff9000)
    /lib/ld-linux-armhf.so.3 (0x76fd6000)
  libpthread.so.0 => /lib/arm-linux-gnueabihf/libpthread.so.0 (0x762e3000)
  librt.so.1 => /lib/arm-linux-gnueabihf/librt.so.1 (0x762d3000)
    libm.so.6 => /lib/arm-linux-gnueabihf/libm.so.6 (0x76262000)
    libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0x76131000)

Codec Dependencies

H.264 is installed by default. Make sure you have purchased and installed MPEG-2 license from the Raspberry Pi store. [http://www.raspberrypi.com/license-keys/]

Conclusions and Next Steps

Missing features

• Deinterlacing
• Changing Picture Size
• PID filtering
• Setting H264 codec parameters like profile etc.