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• C flags which gives priority to quality for decoded images in ffmpeg

  18 janvier 2016, par Tank2005

  I’m trying to decode h.264 streaming with ffmpeg(latest version) on Android NDK.

  I succeeded to get a decoded frame. But, an aquired image is very dirty even if low latency flag is disabled.

  If I want to give priority to quality over decoding speed, which flags should I specify ?

  bool initCodec(bool low_latency)
  
  {
  
      av_register_all();
  
  
  
      codec = avcodec_find_decoder(AV_CODEC_ID_H264);
  
      if(!codec) return false;
  
  
  
      context = avcodec_alloc_context3(codec);
  
      if(!context) return false;
  
  
  
      if(codec->capabilities & CODEC_CAP_TRUNCATED) context->flags |= CODEC_FLAG_TRUNCATED;
  
      if(low_latency == true) context->flags |= CODEC_FLAG_LOW_DELAY;
  
  
  
      frame = av_frame_alloc();
  
  
  
      int res = avcodec_open2(context, codec, NULL);
  
      if (res < 0) {
  
          qDebug() << "Coundn't open codec :" << res;
  
          return false;
  
      }
  
  
  
      av_init_packet(&avpkt);
  
      return true;
  
  }
  
  
  
  void sendBytes(unsigned char *buf, int buflen)
  
  {
  
      avpkt.size = buflen;
  
      avpkt.data = buf;
  
  
  
      int got_frame, len;
  
      while (avpkt.size > 0) {
  
          len = avcodec_decode_video2(context, frame, &got_frame, &avpkt);
  
          if (len < 0) {
  
              qDebug() << "Error while decoding : " << len;
  
              break;
  
          }
  
          if (got_frame) {
  
              onGotFrame(frame);
  
          }
  
          avpkt.size -= len;
  
          avpkt.data += len;
  
      }
  
  }

  

  Ex : I heard that it made a problem while compiling the library. So I write a compile option here(I built it on OpenSUSE Linux).

  #!/bin/bash
  
  NDK=/home/ndk
  
  SYSROOT=$NDK/platforms/android-9/arch-arm/
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
  
  function build_one
  
  {
  
  ./configure \
  
  --prefix=$PREFIX \
  
  --enable-shared \
  
  --disable-static \
  
  --disable-avdevice \
  
  --disable-doc \
  
  --disable-symver \
  
  --disable-encoders \
  
  --disable-decoders \
  
  --enable-decoder=h264 \
  
  --enable-decoder=aac \
  
  --disable-protocols \
  
  --disable-demuxers \
  
  --disable-muxers \
  
  --disable-filters \
  
  --disable-network \
  
  --disable-parsers \
  
  --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
  --target-os=linux \
  
  --arch=arm \
  
  --enable-asm --enable-yasm \
  
  --enable-cross-compile \
  
  --sysroot=$SYSROOT \
  
  --extra-cflags="-Os -marm -march=armv7-a -mfloat-abi=softfp -mfpu=neon" \
  
  --extra-ldflags="-Wl,--fix-cortex-a8" \
  
  $ADDITIONAL_CONFIGURE_FLAG
  
  make clean
  
  make
  
  make install
  
  }
  
  CPU=armv7-a
  
  PREFIX=$(pwd)/android/$CPU
  
  build_on

• How to config ffmpeg with android on eclipse using windows 7 64 bit ?

  25 janvier 2016, par Mahmoud Alnouno

  I’m using ffmpeg version 2.8.5 (last version)
  and ndk version r10e (last version)
  to compile ffmpeg for a android
  I’m using this script bulid_android.sh

  #!/usr/bin/env bash
  
  NDK=D:/AndroidNDK/android-ndk-r10e
  
  SYSROOT=$NDK/platforms/android-18/arch-arm/
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/windows-x86_64
  
  function build_one
  
  {
  
  ./configure \
  
      --arch=arm \
  
      --target-os=android \
  
      --enable-runtime-cpudetect \
  
      --enable-pic \
  
      --disable-shared \
  
      --enable-static \
  
      --extra-cflags='-march=armv6' \
  
      --extra-ldflags="$ADDI_LDFLAGS" \
  
      --enable-ffmpeg \
  
      --disable-ffplay \
  
      --disable-ffprobe \
  
      --disable-ffserver\
  
      --disable-network \
  
      --enable-cross-compile \
  
      --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
      --sysroot=$SYSROOT \
  
      $ADDITIONAL_CONFIGURE_FLAG
  
  make clean
  
  make -j4
  
  make install
  
  }
  
  
  
  CPU=arm
  
  PREFIX=$(pwd)/android/$CPU
  
  ADDI_CFLAGS="-marm"
  
  build_one

  I enter this cmd using msys

  chmod +x build_android.sh

  and this

  ./build_android.sh

  I get this error :

  -gcc is unable to create an executable file.
  
  C compiler test failed.

  help me how to resolve this problem ?

• lavc/lpc : exploit even symmetry of window function

  9 mars 2016, par Ganesh Ajjanagadde

  lavc/lpc : exploit even symmetry of window function
  Yields 2x improvement in function performance, and boosts aac encoding
  
  speed by 4% overall. Sample benchmark (Haswell+GCC under -march=native) :
  
  after :
  
  ffmpeg -i sin.flac -acodec aac -y sin_new.aac  5.22s user 0.03s system 105% cpu 4.970 total
  before :
  
  ffmpeg -i sin.flac -acodec aac -y sin_new.aac  5.40s user 0.05s system 105% cpu 5.162 total
  Reviewed-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanag@gmail.com>
  

  • [DH] libavcodec/lpc.c