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• Unwrap mp4 from flv video

  16 mai 2012, par Matt C

  I used ffmpeg to wrap an mp4 (h264) file in an flv container. I need to do this to inject metadata into the flv for pseudostreaming to Flash players.

  My question, once the wrapped flv file is on my server, is there a way to output the mp4 file to a browser using PHP ? That way I can just have the one flv file, but send it as an mp4 to mobile devices and as an flv to Flash capable devices ?

  From what I understand the mp4 was not re-encoded, but just given a flv header. I am hoping there is a way to get the mp4 data and spit it out on the fly.

• Should I use the MP3 or AAC codec for a .mp4 file ?

  8 novembre 2014, par Justin Jenkins

  We have an encoding process in place using ffmpeg on Mac OS X. This process will take a source video and a couple files from that : .m3u8 video, .mp4 video and .mp3 audio file.

  By default we’ve used the video from our m3u8 process which is a h264 (via libx264) video with AAC (via libfaac) audio.

  We are mostly using these videos on mobile devices (hence the m3u8 files) but we also use the .mp4 files for Android, Windows Phone, etc. More and more we also need to offer these same videos on the web via either a flash player or HTML5 player.

  Therefore, we’d like to have the best audio/video codec combo for all these uses ... where I’m confused is to what is "standard" for a .mp4 file ?

  If the .mp4 uses the mp3 codec then it plays just fine everywhere but QuickTime, in QuickTime the video plays but there is not audio (works just fine in VLC player tho.)

  I’ve been told it’s due to how QuickTime uses file extensions to assume information about the video instead of trying to actually get the codec data from the file ? This does make some sense, if we encode the same file but use AAC for the audio codec then it works just fine in QuickTime.

  So --- what’s the "correct" or "ideal" audio/video codec combo --- is it best and safe to use AAC (i.e. will it work on a broad range of devices) even though it’s not a "free" codec ?

• How to solve bad instruction `vadd.i16 q0,q0,q0' when attempting to check gcc for neon instruction

  6 juillet 2012, par newentry

  Checking  gcc supports failed for neon instruction vadd.i16 q0,q0,q0
  
      test.c
  
  
  
      int main ()
  
      {
  
       __asm__("vadd.i16 q0, q0, q0"); return 0;
  
      }
  
  
  
      arm-linux-androideabi-gcc test.c
  
      /tmp/ccfc8m0G.s: Assembler messages:
  
      /tmp/ccfc8m0G.s:24: Error: bad instruction `vadd.i16 q0,q0,q0'

  Tried with flags -mcpu=cortex-a8 -mfpu=neon but stil no success

  Above code was used to test gcc support for neon instruction.

  Actually i am trying to build x264 with NEON support for ARM platformAfter running configure script
  x264 config log file contains

  Command line options : "—cross-prefix=arm-linux-androideabi-" "—enable-pic" "—extra- cflags=-mcpu=cortex-a8" "—host=arm-linux"

  checking whether arm-linux-androideabi-gcc works... yes
  
  checking whether arm-linux-androideabi-gcc supports for( int i = 0; i < 9; i++ ); with -std=gnu99... yes
  
  checking whether arm-linux-androideabi-gcc supports __asm__("rev ip, ip");... yes
  
  checking whether arm-linux-androideabi-gcc supports __asm__("movt r0, #0");... yes
  
  checking whether arm-linux-androideabi-gcc supports __asm__("vadd.i16 q0, q0, q0");... no
  
  
  
  arm-linux-androideabi-gcc conftest.c  -Wall -I. -I$(SRCPATH) -mcpu=cortex-a8 -std=gnu99    -lm -o conftest
  
  E:\cygwin\tmp\ccVtVI1i.s: Assembler messages:
  
  E:\cygwin\tmp\ccVtVI1i.s:24: Error: bad instruction `vadd.i16 q0,q0,q0'
  
  --------------------------------------------------
  
  Failed program was:
  
  --------------------------------------------------
  
  int main () { __asm__("vadd.i16 q0, q0, q0"); return 0; }
  
  --------------------------------------------------
  
  
  
  
  
  config.h contains
  
  
  
  #define HAVE_MALLOC_H 1
  
  #define HAVE_ARMV6 1
  
  #define HAVE_ARMV6T2 1
  
  #define ARCH_ARM 1
  
  #define SYS_LINUX 1
  
  #define HAVE_VECTOREXT 1
  
  #define fseek fseeko
  
  #define ftell ftello
  
  #define HAVE_GPL 1
  
  #define HAVE_INTERLACED 1
  
  #define HAVE_ALTIVEC 0
  
  #define HAVE_ALTIVEC_H 0
  
  #define HAVE_MMX 0
  
  #define HAVE_NEON 0
  
  #define HAVE_BEOSTHREAD 0
  
  #define HAVE_POSIXTHREAD 0
  
  #define HAVE_WIN32THREAD 0
  
  #define HAVE_THREAD 0
  
  #define HAVE_LOG2F 0
  
  #define HAVE_VISUALIZE 0
  
  #define HAVE_SWSCALE 0
  
  #define HAVE_LAVF 0
  
  #define HAVE_FFMS 0
  
  #define HAVE_GPAC 0
  
  #define HAVE_GF_MALLOC 0
  
  #define HAVE_AVS 0
  
  #define HAVE_CPU_COUNT 0
  
  
  
  
  
  Running make command build x264 static lib  based on above config.h which contains HAVE_NEON 0
  
  
  
  
  
  **Compiler Version**
  
  
  
  
  
  
  
  arm-linux-androideabi-gcc -v
  
  Using built-in specs.
  
  Target: arm-linux-androideabi
  
  Configured with: /tmp/ndk-digit/src/build/../gcc/gcc-4.4.3/configure --prefix=/usr/local/google/digit/repo/opensource/ndk/toolchains/arm-linux-androideabi-4.4.3/prebuilt/windows --target=arm-linux-androideabi --host=i586-mingw32msvc --build=x86_64-linux-gnu --with-gnu-as --with-gnu-ld --enable-languages=c,c++ --with-gmp=/tmp/ndk-digit/build/toolchain/temp-install --with-mpfr=/tmp/ndk-digit/build/toolchain/temp-install --disable-libssp --enable-threads --disable-nls --disable-libmudflap --disable
  
  -libgomp --disable-libstdc__-v3 --disable-sjlj-exceptions --disable-shared --disable-tls --with-float=soft --with-fpu=vfp --with-arch=armv5te --enable-target-optspace --enable-initfini-array --disable-nls --prefix=/usr/local/google/digit/repo/opensource/ndk/toolchains/arm-linux-androideabi-4.4.3/prebuilt/windows --with-sysroot=/usr/local/google/digit/repo/opensource/ndk/toolchains/arm-linux-androideabi-4.4.3/prebuilt/windows/sysroot --with-binutils-version=2.20.1 --with-mpfr-version=2.4.1 --with
  
  -gmp-version=4.2.4 --with-gcc-version=4.4.3 --with-gdb-version=6.6 --with-arch=armv5te --program-transform-name='s,^,arm-linux-androideabi-,'
  
  Thread model: posix
  
  gcc version 4.4.3 (GCC)    

  Goal is to utilize neon enabled ARM processor to boost x264 encoder performance...