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• FFMpeg avformat_write_header always returns 0

  24 octobre 2015, par gabe.roze

  We’ve asked a freelancer to build a video encoder with FFMPeg for iOS but there is a bug and the freelancer is no longer available. I very inexperienced in FFMpeg and video encoding and am trying to debug this error.

  From what I understand, we’re attempting to create an output file and create a header for it however, avformat_write_header is always less than zero. If I comment it out, it does not work

  - (BOOL) writeHeaderWithError:(NSError *__autoreleasing *)error {
  
      AVDictionary *options = NULL;
  
  
  
      // Write header for output file
  
      int writeHeaderValue = avformat_write_header(self.formatContext, &options);
  
      if (writeHeaderValue < 0) {
  
          if (error != NULL) {
  
              *error = [FFUtilities errorForAVError:writeHeaderValue];
  
          }
  
          av_dict_free(&options);
  
          return NO;
  
      }
  
      av_dict_free(&options);
  
      return YES;
  
  }

  Below is some relevant code of how we instantiate a FFOutputFile

      - (AVFormatContext*) formatContextForOutputPath:(NSString*)outputPath options:(NSDictionary*)options {
  
      AVFormatContext *outputFormatContext = NULL;
  
      NSString *outputFormatString = [options objectForKey:kFFmpegOutputFormatKey];
  
  
  
      int openOutputValue = avformat_alloc_output_context2(&outputFormatContext, NULL, [outputFormatString UTF8String], [outputPath UTF8String]);
  
      if (openOutputValue < 0) {
  
          avformat_free_context(outputFormatContext);
  
          return nil;
  
      }
  
      return outputFormatContext;
  
  }
  
  
  
  - (void) addOutputStream:(FFOutputStream*)outputStream {
  
      [self.streams addObject:outputStream];
  
  }
  
  
  
  - (id) initWithPath:(NSString *)path options:(NSDictionary *)options {
  
      if (self = [super initWithPath:path options:options]) {
  
          self.formatContext = [self formatContextForOutputPath:path options:options];
  
          self.streams = [NSMutableArray array];
  
          self.bitstreamFilters = [NSMutableSet set];
  
      }
  
      return self;
  
  }

• FFMpeg avformat_write_header always returns < 0

  7 mai 2024, par gabe.roze

  We've asked a freelancer to build a video encoder with FFMPeg for iOS but there is a bug and the freelancer is no longer available. I very inexperienced in FFMpeg and video encoding and am trying to debug this error.

  &#xA;&#xA;

  From what I understand, we're attempting to create an output file and create a header for it however, avformat_write_header is always less than zero. If I comment it out, it does not work

  &#xA;&#xA;

  - (BOOL) writeHeaderWithError:(NSError *__autoreleasing *)error {
    AVDictionary *options = NULL;

    // Write header for output file
    int writeHeaderValue = avformat_write_header(self.formatContext, &options);
    if (writeHeaderValue < 0) {
        if (error != NULL) {
            *error = [FFUtilities errorForAVError:writeHeaderValue];
        }
        av_dict_free(&options);
        return NO;
    }
    av_dict_free(&options);
    return YES;
}


  &#xA;&#xA;

  Below is some relevant code of how we instantiate a FFOutputFile

  &#xA;&#xA;

      - (AVFormatContext*) formatContextForOutputPath:(NSString*)outputPath options:(NSDictionary*)options {
    AVFormatContext *outputFormatContext = NULL;
    NSString *outputFormatString = [options objectForKey:kFFmpegOutputFormatKey];

    int openOutputValue = avformat_alloc_output_context2(&outputFormatContext, NULL, [outputFormatString UTF8String], [outputPath UTF8String]);
    if (openOutputValue < 0) {
        avformat_free_context(outputFormatContext);
        return nil;
    }
    return outputFormatContext;
}

- (void) addOutputStream:(FFOutputStream*)outputStream {
    [self.streams addObject:outputStream];
}

- (id) initWithPath:(NSString *)path options:(NSDictionary *)options {
    if (self = [super initWithPath:path options:options]) {
        self.formatContext = [self formatContextForOutputPath:path options:options];
        self.streams = [NSMutableArray array];
        self.bitstreamFilters = [NSMutableSet set];
    }
    return self;
}


  &#xA;

• avcodec_find_encoder(AV_CODEC_ID_H264) returns null

  28 février 2017, par Monjura Rumi

  I am building an android application which will encode image captured from camera preview and later decode it. I am using ffmpeg library to encode and decode. To build static library with x264 I have used this tutorial. http://dl.dropbox.com/u/22605641/ffmpeg_android/main.html. As a source code of ffmpeg if I use the one downloaded from the link given in tutorial I can built it but can’t build library if i use source code downloaded from here git clone git ://source.ffmpeg.org/ffmpeg.git ffmpeg. I have built library in ubuntu and using it in windows 7 in Eclipse. As I need only h264 encoder and decoder I have used following code for ffmpeg, slightly modified from tutorial.

  #!/bin/bash
  
  
  
  NDK=~/Documents/android-ndk-r8e
  
  PLATFORM=$NDK/platforms/android-8/arch-arm
  
  PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86
  
  PREFIX=/home/android-ffmpeg
  
  
  
  function build_one
  
  {
  
      ./configure --target-os=linux --prefix=$PREFIX \
  
      --enable-cross-compile \
  
      --enable-runtime-cpudetect \
  
      --disable-asm \
  
      --arch=arm \
  
      --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
      --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
  
      --disable-stripping \
  
      --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
  
      --sysroot=$PLATFORM \
  
      --enable-nonfree \
  
      --enable-version3 \
  
      --disable-everything \
  
      --enable-gpl \
  
      --disable-doc \
  
      --enable-avresample \
  
      --disable-ffplay \
  
      --disable-ffserver \
  
      --enable-ffmpeg \
  
      --disable-ffprobe \
  
      --enable-avcodec \
  
      --enable-libx264 \
  
      --enable-encoder=libx264 \
  
      --enable-encoder=libx264rgb \
  
      --enable-decoder=h263 \
  
      --enable-decoder=h264 \
  
      --enable-decoder=svq3 \   
  
      --enable-zlib \
  
      --enable-gpl \
  
      --enable-pic \
  
      --disable-devices \
  
      --disable-avdevice \
  
      --extra-cflags="-I/home/android-ffmpeg/include -fPIC -DANDROID -D__thumb__ -mthumb -Wfatal-errors -Wno-deprecated -mfloat-abi=softfp -mfpu=vfpv3-d16 -marm -march=armv7-a" \
  
      --extra-ldflags="-L/home/android-ffmpeg/lib"
  
  make -j4 install
  
  $PREBUILT/bin/arm-linux-androideabi-ar d libavcodec/libavcodec.a inverse.o
  
  $PREBUILT/bin/arm-linux-androideabi-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -L$PREFIX/lib  -soname libffmpeg.so -shared -nostdlib  -z,noexecstack -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so libavcodec/libavcodec.a libavfilter/libavfilter.a libavresample/libavresample.a libavformat/libavformat.a libavutil/libavutil.a libswscale/libswscale.a -lc -lm -lz -ldl -llog -lx264 --warn-once --dynamic-linker=/system/bin/linker $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/libgcc.a
  
  }
  
  
  
  build_one

  After building library I have been able to build android ndk. A little part of my JNI code is here.

  JNIEXPORT jint JNICALL Java_com_example_testjava_TestjniActivity_initencoder(JNIEnv* env,jobject obj){
  
  
  
      av_register_all();
  
      avcodec_register_all();
  
      codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
      if (!codec) {
  
        __android_log_write(ANDROID_LOG_INFO, "debug", "not found");                
  
         return -1;
  
      }
  
  .
  
  .
  
  .
  
  }

  When I run my java source code that calls initencoder() I get -1 as return value and logcat prints "not found". That means avcodec_find_encoder() returns null and if condition is being ok. I don’t know what’s wrong. Why this function is returning null ? I have searched a lot but did not find any solution that could guide me to right direction. some says to use avcodec_init(). But ndk-build command fails and shows error saying undefined reference to ’avcodec_init()’. I have started with library build because I thought may be I am doing wrong from the first stage. Did I make any mistake in library building like not enabling things that I should ? Please help me here. This is kind of urgent for me.