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• How to write NALs produced by x264_encoder_encode() using ffmpeg av_interleaved_write_frame()

  21 janvier 2013, par Haleeq Usman

  I have been trying to produce a "flv" video file in the following sequence :

  av_register_all();
  
  
  
  // Open video file
  
  if (avformat_open_input(&pFormatCtx, "6.mp4", NULL, NULL) != 0)
  
      return -1; // Couldn't open file
  
  
  
  // Retrieve stream information
  
  if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
  
      return -1; // Couldn't find stream information
  
  
  
  // Dump information about file onto standard error
  
  av_dump_format(pFormatCtx, 0, "input_file.mp4", 0);
  
  
  
  // Find the first video stream
  
  videoStream = -1;
  
  for (i = 0; i < pFormatCtx->nb_streams; i++)
  
      if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          videoStream = i;
  
          break;
  
      }
  
  if (videoStream == -1)
  
      return -1; // Didn't find a video stream
  
  
  
  // Get a pointer to the codec context for the video stream
  
  pCodecCtx = pFormatCtx->streams[videoStream]->codec;
  
  
  
  // Find the decoder for the video stream
  
  pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
  if (pCodec == NULL) {
  
      fprintf(stderr, "Unsupported codec!\n");
  
      return -1; // Codec not found
  
  }
  
  // Open codec
  
  if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
  
      return -1; // Could not open codec
  
  
  
  // Allocate video frame
  
  pFrame = avcodec_alloc_frame();
  
  
  
  // Allocate video frame
  
  pFrame = avcodec_alloc_frame();
  
  
  
  // Allocate an AVFrame structure
  
  pFrameYUV420 = avcodec_alloc_frame();
  
  if (pFrameYUV420 == NULL)
  
      return -1;
  
  
  
  // Determine required buffer size and allocate buffer
  
  numBytes = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
  
  buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
  
  
  
  // Assign appropriate parts of buffer to image planes in pFrameYUV420
  
  // Note that pFrameYUV420 is an AVFrame, but AVFrame is a superset of AVPicture
  
  avpicture_fill((AVPicture *) pFrameRGB, buffer, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
  
  
  
  // Setup scaler
  
  img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, SWS_BILINEAR, 0, 0, 0);
  
  if (img_convert_ctx == NULL) {
  
      fprintf(stderr, "Cannot initialize the conversion context!\n");
  
      exit(1);
  
  }
  
  
  
  // Setup encoder/muxing now
  
  filename = "output_file.flv";
  
  fmt = av_guess_format("flv", filename, NULL);
  
  if (fmt == NULL) {
  
      printf("Could not guess format.\n");
  
      return -1;
  
  }
  
  /* allocate the output media context */
  
  oc = avformat_alloc_context();
  
  if (oc == NULL) {
  
      printf("could not allocate context.\n");
  
      return -1;
  
  }
  
  oc->oformat = fmt;
  
  snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
  
  
  
  video_st = NULL;
  
  if (fmt->video_codec != AV_CODEC_ID_NONE) {
  
      video_st = add_stream(oc, &video_codec, fmt->video_codec);
  
  }
  
  
  
  // Let's see some information about our format
  
  av_dump_format(oc, 0, filename, 1);
  
  
  
  /* open the output file, if needed */
  
  if (!(fmt->flags & AVFMT_NOFILE)) {
  
      ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
  
      if (ret < 0) {
  
          fprintf(stderr, "Could not open '%s': %s\n", filename, av_err2str(ret));
  
          return 1;
  
      }
  
      }
  
  /* Write the stream header, if any. */
  
  ret = avformat_write_header(oc, NULL);
  
  if (ret < 0) {
  
      fprintf(stderr, "Error occurred when opening output file: %s\n", av_err2str(ret));
  
      return 1;
  
  }
  
  
  
  // Setup x264 params
  
  x264_param_t param;
  
  x264_param_default_preset(&param, "veryfast", "zerolatency");
  
  param.i_threads = 1;
  
  param.i_width = video_st->codec->width;
  
  param.i_height = video_st->codec->height;
  
  param.i_fps_num = STREAM_FRAME_RATE; // 30 fps, same as video
  
  param.i_fps_den = 1;
  
  // Intra refres:
  
  param.i_keyint_max = STREAM_FRAME_RATE;
  
  param.b_intra_refresh = 1;
  
  // Rate control:
  
  param.rc.i_rc_method = X264_RC_CRF;
  
  param.rc.f_rf_constant = 25;
  
  param.rc.f_rf_constant_max = 35;
  
  // For streaming:
  
  param.b_repeat_headers = 1;
  
  param.b_annexb = 1;
  
  x264_param_apply_profile(&param, "baseline");
  
  
  
  x264_t* encoder = x264_encoder_open(&param);
  
  x264_picture_t pic_in, pic_out;
  
  x264_picture_alloc(&pic_in, X264_CSP_I420, video_st->codec->width, video_st->codec->height);
  
  
  
  x264_nal_t* nals;
  
  int i_nals;
  
  
  
  // The loop:
  
  // 1. Read frames
  
  // 2. Decode the frame
  
  // 3. Attempt to re-encode using x264
  
  // 4. Write the x264 encoded frame using av_interleaved_write_frame
  
  while (av_read_frame(pFormatCtx, &packet) >= 0) {
  
      // Is this a packet from the video stream?
  
      if (packet.stream_index == videoStream) {
  
          // Decode video frame
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
          // Did we get a video frame?
  
          if (frameFinished) {
  
              sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pic_in.img.plane, pic_in.img.i_stride);
  
              int frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
  
  
  
              if (frame_size >= 0) {
  
                  if (i_nals < 0)
  
                      printf("invalid frame size: %d\n", i_nals);
  
                  // write out NALs
  
                  for (i = 0; i < i_nals; i++) {
  
                      // initalize a packet
  
                      AVPacket p;
  
                      av_init_packet(&p);
  
                      p.data = nals[i].p_payload;
  
                      p.size = nals[i].i_payload;
  
                      p.stream_index = video_st->index;
  
                      p.flags = AV_PKT_FLAG_KEY;
  
                      p.pts = AV_NOPTS_VALUE;
  
                      p.dts = AV_NOPTS_VALUE;
  
                      ret = av_interleaved_write_frame(oc, &p);
  
                  }
  
              }
  
              printf("encoded frame #%d\n", frame_count);
  
              frame_count++;
  
          }
  
      }
  
  
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
  }
  
  
  
  // Now we free up resources used/close codecs, and finally close our program.

  Here is the implementation for the add_stream() function :

  /* Add an output stream. */
  
  static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id) {
  
      AVCodecContext *c;
  
      AVStream *st;
  
      int r;
  
      /* find the encoder */
  
      *codec = avcodec_find_encoder(codec_id);
  
      if (!(*codec)) {
  
          fprintf(stderr, "Could not find encoder for '%s'\n",
  
                  avcodec_get_name(codec_id));
  
          exit(1);
  
      }
  
      st = avformat_new_stream(oc, *codec);
  
      if (!st) {
  
          fprintf(stderr, "Could not allocate stream\n");
  
          exit(1);
  
      }
  
      st->id = oc->nb_streams - 1;
  
      c = st->codec;
  
      switch ((*codec)->type) {
  
      case AVMEDIA_TYPE_AUDIO:
  
          st->id = 1;
  
          c->sample_fmt = AV_SAMPLE_FMT_FLTP;
  
          c->bit_rate = 64000;
  
          c->sample_rate = 44100;
  
          c->channels = 2;
  
          break;
  
      case AVMEDIA_TYPE_VIDEO:
  
          avcodec_get_context_defaults3(c, *codec);
  
          c->codec_id = codec_id;
  
          c->bit_rate = 500*1000;
  
          //c->rc_min_rate = 500*1000;
  
          //c->rc_max_rate = 500*1000;
  
          //c->rc_buffer_size = 500*1000;
  
          /* Resolution must be a multiple of two. */
  
          c->width = 1280;
  
          c->height = 720;
  
          /* timebase: This is the fundamental unit of time (in seconds) in terms
  
           * of which frame timestamps are represented. For fixed-fps content,
  
           * timebase should be 1/framerate and timestamp increments should be
  
           * identical to 1. */
  
          c->time_base.den = STREAM_FRAME_RATE;
  
          c->time_base.num = 1;
  
          c->gop_size = 12; /* emit one intra frame every twelve frames at most */
  
          c->pix_fmt = STREAM_PIX_FMT;
  
          if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
  
              /* just for testing, we also add B frames */
  
              c->max_b_frames = 2;
  
          }
  
          if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
  
              /* Needed to avoid using macroblocks in which some coeffs overflow.
  
               * This does not happen with normal video, it just happens here as
  
               * the motion of the chroma plane does not match the luma plane. */
  
              c->mb_decision = 2;
  
          }
  
          break;
  
      default:
  
          break;
  
      }
  
      /* Some formats want stream headers to be separate. */
  
      if (oc->oformat->flags & AVFMT_GLOBALHEADER)
  
          c->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      return st;
  
  }

  After the encoding is complete, I check the output file output_file.flv. I notice it's size is very large : 101MB and it does not play. If I use ffmpeg to decode/encode the input file, then I get an output file about 83MB in size (which is about the same size as the original .mp4 file used as input). Also, the 83MB output from just using ffmpeg C api, as opposed to using x264 for the encoding step, plays just fine. Does anyone know where I am going wrong ? I have tried researching this for a few days now but with no luck :(. I feel that I am close to making it work, however, I just cannot figure out what I am doing wrong. Thank you !

• How to write NALs produced by x264_encoder_encode() using ffmpeg av_interleaved_write_frame()

  21 janvier 2013, par Haleeq Usman

  I have been trying to produce a "flv" video file in the following sequence :

  av_register_all();
  
  
  
  // Open video file
  
  if (avformat_open_input(&pFormatCtx, "6.mp4", NULL, NULL) != 0)
  
      return -1; // Couldn't open file
  
  
  
  // Retrieve stream information
  
  if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
  
      return -1; // Couldn't find stream information
  
  
  
  // Dump information about file onto standard error
  
  av_dump_format(pFormatCtx, 0, "input_file.mp4", 0);
  
  
  
  // Find the first video stream
  
  videoStream = -1;
  
  for (i = 0; i < pFormatCtx->nb_streams; i++)
  
      if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          videoStream = i;
  
          break;
  
      }
  
  if (videoStream == -1)
  
      return -1; // Didn't find a video stream
  
  
  
  // Get a pointer to the codec context for the video stream
  
  pCodecCtx = pFormatCtx->streams[videoStream]->codec;
  
  
  
  // Find the decoder for the video stream
  
  pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
  if (pCodec == NULL) {
  
      fprintf(stderr, "Unsupported codec!\n");
  
      return -1; // Codec not found
  
  }
  
  // Open codec
  
  if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
  
      return -1; // Could not open codec
  
  
  
  // Allocate video frame
  
  pFrame = avcodec_alloc_frame();
  
  
  
  // Allocate video frame
  
  pFrame = avcodec_alloc_frame();
  
  
  
  // Allocate an AVFrame structure
  
  pFrameYUV420 = avcodec_alloc_frame();
  
  if (pFrameYUV420 == NULL)
  
      return -1;
  
  
  
  // Determine required buffer size and allocate buffer
  
  numBytes = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
  
  buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
  
  
  
  // Assign appropriate parts of buffer to image planes in pFrameYUV420
  
  // Note that pFrameYUV420 is an AVFrame, but AVFrame is a superset of AVPicture
  
  avpicture_fill((AVPicture *) pFrameRGB, buffer, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
  
  
  
  // Setup scaler
  
  img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, SWS_BILINEAR, 0, 0, 0);
  
  if (img_convert_ctx == NULL) {
  
      fprintf(stderr, "Cannot initialize the conversion context!\n");
  
      exit(1);
  
  }
  
  
  
  // Setup encoder/muxing now
  
  filename = "output_file.flv";
  
  fmt = av_guess_format("flv", filename, NULL);
  
  if (fmt == NULL) {
  
      printf("Could not guess format.\n");
  
      return -1;
  
  }
  
  /* allocate the output media context */
  
  oc = avformat_alloc_context();
  
  if (oc == NULL) {
  
      printf("could not allocate context.\n");
  
      return -1;
  
  }
  
  oc->oformat = fmt;
  
  snprintf(oc->filename, sizeof(oc->filename), "%s", filename);
  
  
  
  video_st = NULL;
  
  if (fmt->video_codec != AV_CODEC_ID_NONE) {
  
      video_st = add_stream(oc, &video_codec, fmt->video_codec);
  
  }
  
  
  
  // Let's see some information about our format
  
  av_dump_format(oc, 0, filename, 1);
  
  
  
  /* open the output file, if needed */
  
  if (!(fmt->flags & AVFMT_NOFILE)) {
  
      ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
  
      if (ret < 0) {
  
          fprintf(stderr, "Could not open '%s': %s\n", filename, av_err2str(ret));
  
          return 1;
  
      }
  
      }
  
  /* Write the stream header, if any. */
  
  ret = avformat_write_header(oc, NULL);
  
  if (ret < 0) {
  
      fprintf(stderr, "Error occurred when opening output file: %s\n", av_err2str(ret));
  
      return 1;
  
  }
  
  
  
  // Setup x264 params
  
  x264_param_t param;
  
  x264_param_default_preset(&param, "veryfast", "zerolatency");
  
  param.i_threads = 1;
  
  param.i_width = video_st->codec->width;
  
  param.i_height = video_st->codec->height;
  
  param.i_fps_num = STREAM_FRAME_RATE; // 30 fps, same as video
  
  param.i_fps_den = 1;
  
  // Intra refres:
  
  param.i_keyint_max = STREAM_FRAME_RATE;
  
  param.b_intra_refresh = 1;
  
  // Rate control:
  
  param.rc.i_rc_method = X264_RC_CRF;
  
  param.rc.f_rf_constant = 25;
  
  param.rc.f_rf_constant_max = 35;
  
  // For streaming:
  
  param.b_repeat_headers = 1;
  
  param.b_annexb = 1;
  
  x264_param_apply_profile(&param, "baseline");
  
  
  
  x264_t* encoder = x264_encoder_open(&param);
  
  x264_picture_t pic_in, pic_out;
  
  x264_picture_alloc(&pic_in, X264_CSP_I420, video_st->codec->width, video_st->codec->height);
  
  
  
  x264_nal_t* nals;
  
  int i_nals;
  
  
  
  // The loop:
  
  // 1. Read frames
  
  // 2. Decode the frame
  
  // 3. Attempt to re-encode using x264
  
  // 4. Write the x264 encoded frame using av_interleaved_write_frame
  
  while (av_read_frame(pFormatCtx, &packet) >= 0) {
  
      // Is this a packet from the video stream?
  
      if (packet.stream_index == videoStream) {
  
          // Decode video frame
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
          // Did we get a video frame?
  
          if (frameFinished) {
  
              sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pic_in.img.plane, pic_in.img.i_stride);
  
              int frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
  
  
  
              if (frame_size >= 0) {
  
                  if (i_nals < 0)
  
                      printf("invalid frame size: %d\n", i_nals);
  
                  // write out NALs
  
                  for (i = 0; i < i_nals; i++) {
  
                      // initalize a packet
  
                      AVPacket p;
  
                      av_init_packet(&p);
  
                      p.data = nals[i].p_payload;
  
                      p.size = nals[i].i_payload;
  
                      p.stream_index = video_st->index;
  
                      p.flags = AV_PKT_FLAG_KEY;
  
                      p.pts = AV_NOPTS_VALUE;
  
                      p.dts = AV_NOPTS_VALUE;
  
                      ret = av_interleaved_write_frame(oc, &p);
  
                  }
  
              }
  
              printf("encoded frame #%d\n", frame_count);
  
              frame_count++;
  
          }
  
      }
  
  
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
  }
  
  
  
  // Now we free up resources used/close codecs, and finally close our program.

  Here is the implementation for the add_stream() function :

  /* Add an output stream. */
  
  static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id) {
  
      AVCodecContext *c;
  
      AVStream *st;
  
      int r;
  
      /* find the encoder */
  
      *codec = avcodec_find_encoder(codec_id);
  
      if (!(*codec)) {
  
          fprintf(stderr, "Could not find encoder for '%s'\n",
  
                  avcodec_get_name(codec_id));
  
          exit(1);
  
      }
  
      st = avformat_new_stream(oc, *codec);
  
      if (!st) {
  
          fprintf(stderr, "Could not allocate stream\n");
  
          exit(1);
  
      }
  
      st->id = oc->nb_streams - 1;
  
      c = st->codec;
  
      switch ((*codec)->type) {
  
      case AVMEDIA_TYPE_AUDIO:
  
          st->id = 1;
  
          c->sample_fmt = AV_SAMPLE_FMT_FLTP;
  
          c->bit_rate = 64000;
  
          c->sample_rate = 44100;
  
          c->channels = 2;
  
          break;
  
      case AVMEDIA_TYPE_VIDEO:
  
          avcodec_get_context_defaults3(c, *codec);
  
          c->codec_id = codec_id;
  
          c->bit_rate = 500*1000;
  
          //c->rc_min_rate = 500*1000;
  
          //c->rc_max_rate = 500*1000;
  
          //c->rc_buffer_size = 500*1000;
  
          /* Resolution must be a multiple of two. */
  
          c->width = 1280;
  
          c->height = 720;
  
          /* timebase: This is the fundamental unit of time (in seconds) in terms
  
           * of which frame timestamps are represented. For fixed-fps content,
  
           * timebase should be 1/framerate and timestamp increments should be
  
           * identical to 1. */
  
          c->time_base.den = STREAM_FRAME_RATE;
  
          c->time_base.num = 1;
  
          c->gop_size = 12; /* emit one intra frame every twelve frames at most */
  
          c->pix_fmt = STREAM_PIX_FMT;
  
          if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
  
              /* just for testing, we also add B frames */
  
              c->max_b_frames = 2;
  
          }
  
          if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
  
              /* Needed to avoid using macroblocks in which some coeffs overflow.
  
               * This does not happen with normal video, it just happens here as
  
               * the motion of the chroma plane does not match the luma plane. */
  
              c->mb_decision = 2;
  
          }
  
          break;
  
      default:
  
          break;
  
      }
  
      /* Some formats want stream headers to be separate. */
  
      if (oc->oformat->flags & AVFMT_GLOBALHEADER)
  
          c->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      return st;
  
  }

  After the encoding is complete, I check the output file output_file.flv. I notice it's size is very large : 101MB and it does not play. If I use ffmpeg to decode/encode the input file, then I get an output file about 83MB in size (which is about the same size as the original .mp4 file used as input). Also, the 83MB output from just using ffmpeg C api, as opposed to using x264 for the encoding step, plays just fine. Does anyone know where I am going wrong ? I have tried researching this for a few days now but with no luck :(. I feel that I am close to making it work, however, I just cannot figure out what I am doing wrong. Thank you !

• FFmpeg not honoring bitrate for different containers ?

  19 mars 2013, par Haleeq Usman

  I am attempting to encode a mp4 video file into a flv video. Here is what I am doing :

  #include 
  
  #include 
  
  #include 
  
  #include 
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  
  
  #define STREAM_FRAME_RATE 30 /* 30 images/s */
  
  #define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */
  
  /**************************************************************/
  
  /* Add an output stream. */
  
  static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec,
  
          enum AVCodecID codec_id) {
  
      AVCodecContext *c;
  
      AVStream *st;
  
      /* find the encoder */
  
      *codec = avcodec_find_encoder(codec_id);
  
      if (!(*codec)) {
  
          fprintf(stderr, "Could not find encoder for &#39;%s&#39;\n",
  
                  avcodec_get_name(codec_id));
  
          exit(1);
  
      }
  
      st = avformat_new_stream(oc, *codec);
  
      if (!st) {
  
          fprintf(stderr, "Could not allocate stream\n");
  
          exit(1);
  
      }
  
      st->id = oc->nb_streams - 1;
  
      c = st->codec;
  
      switch ((*codec)->type) {
  
      case AVMEDIA_TYPE_VIDEO:
  
          //avcodec_get_context_defaults3(c, *codec);
  
          c->codec_id = codec_id;
  
          c->bit_rate = 150 * 1000; //2314000;;
  
          //c->rc_max_rate = 150*1000;
  
          //c->rc_buffer_size = 150*1000;
  
          /* Resolution must be a multiple of two. */
  
          c->width = 1280;
  
          c->height = 720;
  
          /* timebase: This is the fundamental unit of time (in seconds) in terms
  
           * of which frame timestamps are represented. For fixed-fps content,
  
           * timebase should be 1/framerate and timestamp increments should be
  
           * identical to 1. */
  
          c->time_base.den = STREAM_FRAME_RATE;
  
          c->time_base.num = 1;
  
          c->gop_size = 12; /* emit one intra frame every twelve frames at most */
  
          c->pix_fmt = STREAM_PIX_FMT;
  
          if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
  
              /* just for testing, we also add B frames */
  
              c->max_b_frames = 2;
  
          }
  
          if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
  
              /* Needed to avoid using macroblocks in which some coeffs overflow.
  
               * This does not happen with normal video, it just happens here as
  
               * the motion of the chroma plane does not match the luma plane. */
  
              c->mb_decision = 2;
  
          }
  
          break;
  
      default:
  
          break;
  
      }
  
      /* Some formats want stream headers to be separate. */
  
      if (oc->oformat->flags &amp; AVFMT_GLOBALHEADER)
  
          c->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      return st;
  
  }
  
  /**************************************************************/
  
  /* video output */
  
  static AVFrame *frame;
  
  static AVPicture src_picture, dst_picture;
  
  static int frame_count;
  
  static void open_video(AVFormatContext *oc, AVCodec *codec, AVStream *st) {
  
      int ret;
  
      AVCodecContext *c = st->codec;
  
      /* open the codec */
  
      ret = avcodec_open2(c, codec, NULL);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not open video codec: %s\n", av_err2str(ret));
  
          exit(1);
  
      }
  
      /* allocate and init a re-usable frame */
  
      frame = avcodec_alloc_frame();
  
      if (!frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
      /* Allocate the encoded raw picture. */
  
      ret = avpicture_alloc(&amp;dst_picture, c->pix_fmt, c->width, c->height);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not allocate picture: %s\n", av_err2str(ret));
  
          exit(1);
  
      }
  
      /* If the output format is not YUV420P, then a temporary YUV420P
  
       * picture is needed too. It is then converted to the required
  
       * output format. */
  
      if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
  
          ret = avpicture_alloc(&amp;src_picture, AV_PIX_FMT_YUV420P, c->width,
  
                  c->height);
  
          if (ret &lt; 0) {
  
              fprintf(stderr, "Could not allocate temporary picture: %s\n",
  
                      av_err2str(ret));
  
              exit(1);
  
          }
  
      }
  
      /* copy data and linesize picture pointers to frame */
  
      *((AVPicture *) frame) = dst_picture;
  
  }
  
  static void close_video(AVFormatContext *oc, AVStream *st) {
  
      avcodec_close(st->codec);
  
      av_free(src_picture.data[0]);
  
      av_free(dst_picture.data[0]);
  
      av_free(frame);
  
  }
  
  
  
  int main(int argc, char *argv[]) {
  
      AVFormatContext *pFormatCtx = NULL;
  
      int i, videoStream;
  
      AVCodecContext *pCodecCtx = NULL;
  
      AVCodec *pCodec;
  
      AVFrame *pFrame;
  
      AVPacket packet;
  
      int frameFinished;
  
  
  
      const char *filename;
  
      AVOutputFormat *fmt;
  
      AVFormatContext *oc;
  
      AVStream *video_st;
  
      AVCodec *video_codec;
  
      int ret;
  
  
  
      // Register all formats, codecs and network
  
      av_register_all();
  
      avcodec_register_all();
  
      avformat_network_init();
  
  
  
      // Open video file
  
      if (avformat_open_input(&amp;pFormatCtx, "input_file.mp4", NULL, NULL) != 0)
  
          return -1; // Couldn&#39;t open file
  
  
  
      // Retrieve stream information
  
      if (avformat_find_stream_info(pFormatCtx, NULL) &lt; 0)
  
          return -1; // Couldn&#39;t find stream information
  
  
  
      // Dump information about file onto standard error
  
      av_dump_format(pFormatCtx, 0, "input_file.mp4", 0);
  
  
  
      // Find the first video stream
  
      videoStream = -1;
  
      for (i = 0; i &lt; pFormatCtx->nb_streams; i++)
  
          if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
              videoStream = i;
  
              break;
  
          }
  
      if (videoStream == -1)
  
          return -1; // Didn&#39;t find a video stream
  
  
  
      // Get a pointer to the codec context for the video stream
  
      pCodecCtx = pFormatCtx->streams[videoStream]->codec;
  
  
  
      // Find the decoder for the video stream
  
      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if (pCodec == NULL) {
  
          fprintf(stderr, "Unsupported codec!\n");
  
          return -1; // Codec not found
  
      }
  
      // Open codec
  
      if (avcodec_open2(pCodecCtx, pCodec, NULL) &lt; 0)
  
          return -1; // Could not open codec
  
  
  
      // Allocate video frame
  
      pFrame = avcodec_alloc_frame();
  
  
  
      // setup mux
  
      filename = "output_file.flv";
  
      fmt = av_guess_format("flv", filename, NULL);
  
      if (fmt == NULL) {
  
          printf("Could not guess format.\n");
  
          return -1;
  
      }
  
      // allocate the output media context
  
      oc = avformat_alloc_context();
  
      if (oc == NULL) {
  
          printf("could not allocate context.\n");
  
          return -1;
  
      }
  
      oc->oformat = fmt;
  
  
  
      // Add the video streams using the default format codecs
  
      // and initialize the codecs.
  
      video_st = NULL;
  
      if (fmt->video_codec != AV_CODEC_ID_NONE) {
  
          video_st = add_stream(oc, &amp;video_codec, fmt->video_codec);
  
      }
  
      // Now that all the parameters are set, we can open the
  
      // video codec and allocate the necessary encode buffers.
  
      if (video_st)
  
          open_video(oc, video_codec, video_st);
  
  
  
      /* open the output file, if needed */
  
      if (!(fmt->flags &amp; AVFMT_NOFILE)) {
  
          ret = avio_open(&amp;oc->pb, filename, AVIO_FLAG_WRITE);
  
          if (ret &lt; 0) {
  
              fprintf(stderr, "Could not open &#39;%s&#39;: %s\n", filename,
  
                      av_err2str(ret));
  
              return 1;
  
          }
  
      }
  
  
  
      // dump output format
  
      av_dump_format(oc, 0, filename, 1);
  
  
  
      // Write the stream header, if any.
  
      ret = avformat_write_header(oc, NULL);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Error occurred when opening output file: %s\n",
  
                  av_err2str(ret));
  
          return 1;
  
      }
  
  
  
      // Read frames, decode, and re-encode
  
      while (av_read_frame(pFormatCtx, &amp;packet) >= 0) {
  
          // Is this a packet from the video stream?
  
          if (packet.stream_index == videoStream) {
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet);
  
  
  
              // Did we get a video frame?
  
              if (frameFinished) {
  
  
  
                  AVFrame* newFrame = avcodec_alloc_frame(); // Initialize a new frame
  
                  int size = avpicture_get_size(video_st->codec->pix_fmt,
  
                          video_st->codec->width, video_st->codec->height);
  
                  uint8_t* picture_buf = av_malloc(size);
  
  
  
                  avpicture_fill((AVPicture *) newFrame, picture_buf,
  
                          video_st->codec->pix_fmt, video_st->codec->width,
  
                          video_st->codec->height);
  
  
  
                  // Copy only the frame content without any other disturbing
  
                  av_picture_copy((AVPicture*) newFrame, (AVPicture*) pFrame,
  
                          video_st->codec->pix_fmt, video_st->codec->width,
  
                          video_st->codec->height);
  
  
  
                  // encode the image
  
                  AVPacket pkt;
  
                  int got_output;
  
                  av_init_packet(&amp;pkt);
  
                  pkt.data = NULL; // packet data will be allocated by the encoder
  
                  pkt.size = 0;
  
  
  
                  /* Setting newFrame->pts this way produces the error &#39;non-strictly-monotonic PTS&#39; */
  
                  //if(newFrame->pts != AV_NOPTS_VALUE)
  
                  //newFrame->pts = av_rescale_q(newFrame->pts, video_st->time_base, video_st->codec->time_base);
  
  
  
                  // Setting newFrame->pts this does not produce &#39;non-strictly-monotonic PTS&#39;
  
                  newFrame->pts = frame_count;
  
  
  
                  ret = avcodec_encode_video2(video_st->codec, &amp;pkt, newFrame, &amp;got_output);
  
                  if (ret &lt; 0) {
  
                      fprintf(stderr, "Error encoding video frame: %s\n", av_err2str(ret));
  
                      exit(1);
  
                  }
  
  
  
                  if (got_output) {
  
                      if (video_st->codec->coded_frame->key_frame)
  
                      pkt.flags |= AV_PKT_FLAG_KEY;
  
                      pkt.stream_index = video_st->index;
  
  
  
                      if (pkt.pts != AV_NOPTS_VALUE)
  
                          pkt.pts = av_rescale_q(pkt.pts,
  
                                  video_st->codec->time_base,
  
                                  video_st->time_base);
  
                      if (pkt.dts != AV_NOPTS_VALUE)
  
                          pkt.dts = av_rescale_q(pkt.dts,
  
                                  video_st->codec->time_base,
  
                                  video_st->time_base);
  
  
  
                      // Write the compressed frame to the media file.
  
                      ret = av_interleaved_write_frame(oc, &amp;pkt);
  
                  } else {
  
                      ret = 0;
  
                  }
  
                  if (ret != 0) {
  
                      fprintf(stderr, "Error while writing video frame: %s\n",
  
                              av_err2str(ret));
  
                      exit(1);
  
                  }
  
  
  
                  fprintf(stderr, "encoded frame #%d\n", frame_count);
  
                  frame_count++;
  
                  av_free(picture_buf);
  
                  av_free_packet(&amp;pkt);
  
              }
  
          }
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&amp;packet);
  
      }
  
  
  
      /* Write the trailer, if any. The trailer must be written before you
  
       * close the CodecContexts open when you wrote the header; otherwise
  
       * av_write_trailer() may try to use memory that was freed on
  
       * av_codec_close(). */
  
      av_write_trailer(oc);
  
  
  
      /* Close video encoder (codec). */
  
      if (video_st)
  
          close_video(oc, video_st);
  
      // Free the streams.
  
      for (i = 0; i &lt; oc->nb_streams; i++) {
  
          av_freep(&amp;oc->streams[i]->codec);
  
          av_freep(&amp;oc->streams[i]);
  
      }
  
      if (!(fmt->flags &amp; AVFMT_NOFILE))
  
          /* Close the output file. */
  
          avio_close(oc->pb);
  
      /* free the stream */
  
      av_free(oc);
  
  
  
      // Free the YUV frame holding decoded frame
  
      av_free(pFrame);
  
  
  
      // Close the decoder (codec)
  
      avcodec_close(pCodecCtx);
  
  
  
      // Close the input video file
  
      avformat_close_input(&amp;pFormatCtx);
  
  
  
      return 0;
  
  }

  If I change the output format to an mp4, mov, or f4v by changing :

  // setup mux (FLV OUTPUT)
  
  filename = "output_file.flv";
  
  fmt = av_guess_format("flv", filename, NULL);
  
  if (fmt == NULL) {
  
      printf("Could not guess format.\n");
  
      return -1;
  
  }

  to

  // setup mux (MP4 OUTPUT)
  
  filename = "output_file.mp4";
  
  fmt = av_guess_format("mp4", filename, NULL);
  
  if (fmt == NULL) {
  
      printf("Could not guess format.\n");
  
      return -1;
  
  }

  Then the bitrate is honored. Here is the output of running with a mp4 output

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input_file.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isomavc1mp42
  
      creation_time   : 2010-02-09 19:11:10
  
    Duration: 00:04:31.80, start: 0.000000, bitrate: 2314 kb/s
  
      Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s
  
      Metadata:
  
        creation_time   : 2010-02-09 19:11:10
  
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
  
      Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 2186 kb/s, 30 fps, 30 tbr, 30k tbn, 60 tbc
  
      Metadata:
  
        creation_time   : 2010-02-09 19:11:10
  
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
  
  [libx264 @ 02268b80] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 AVX
  
  [libx264 @ 02268b80] profile High, level 3.1
  
  [libx264 @ 02268b80] 264 - core 129 r2230 1cffe9f - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deb
  
  lock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chro
  
  ma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
  
   b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=12 keyint_min=1 scenecut=40 intra_refresh=0 rc_lookahead=12 rc=abr mbtree=1 bitrate=150 ratetol=1.0 qco
  
  mp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'output_file.mp4':
  
      Stream #0:0: Video: h264, yuv420p, 1280x720, q=-1--1, 150 kb/s, 90k tbn, 30 tbc
  
  encoded frame #0
  
  encoded frame #1
  
  encoded frame #2
  
  encoded frame #3
  
  .
  
  .
  
  .
  
  encoded frame #8142
  
  encoded frame #8143
  
  encoded frame #8144
  
  encoded frame #8145
  
  [libx264 @ 02174240] frame I:771   Avg QP:47.71  size:  2739
  
  [libx264 @ 02174240] frame P:5083  Avg QP:50.05  size:   833
  
  [libx264 @ 02174240] frame B:2264  Avg QP:48.16  size:    91
  
  [libx264 @ 02174240] consecutive B-frames: 59.6%  6.4%  9.0% 24.9%
  
  [libx264 @ 02174240] mb I  I16..4: 34.0% 65.8%  0.2%
  
  [libx264 @ 02174240] mb P  I16..4:  6.8%  3.0%  0.0%  P16..4:  8.5%  0.4%  1.7%  0.0%  0.0%    skip:79.6%
  
  [libx264 @ 02174240] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  1.8%  0.0%  0.0%  direct: 0.0%  skip:98.2%  L0:23.6% L1:76.4% BI: 0.0%
  
  [libx264 @ 02174240] final ratefactor: 57.62
  
  [libx264 @ 02174240] 8x8 transform intra:52.1% inter:98.5%
  
  [libx264 @ 02174240] coded y,uvDC,uvAC intra: 3.1% 14.0% 0.2% inter: 0.1% 0.4% 0.0%
  
  [libx264 @ 02174240] i16 v,h,dc,p: 69% 23%  4%  4%
  
  [libx264 @ 02174240] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 23%  6% 68%  1%  1%  1%  1%  0%  0%
  
  [libx264 @ 02174240] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 41% 18% 18%  4%  4%  5%  3%  3%  3%
  
  [libx264 @ 02174240] i8c dc,h,v,p: 98%  1%  1%  0%
  
  [libx264 @ 02174240] Weighted P-Frames: Y:2.1% UV:1.2%
  
  [libx264 @ 02174240] ref P L0: 72.4%  0.8% 19.1%  7.6%  0.1%
  
  [libx264 @ 02174240] ref B L0: 89.8%  9.1%  1.2%
  
  [libx264 @ 02174240] ref B L1: 96.2%  3.8%
  
  [libx264 @ 02174240] kb/s:193.62

  The final file size of output_file.mp4 is about 6.5MB and using ffplay, I notice that bitrate was honored. Of course the quality itself shows.

  Here is the output of running with a flv output :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input_file.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isomavc1mp42
  
      creation_time   : 2010-02-09 19:11:10
  
    Duration: 00:04:31.80, start: 0.000000, bitrate: 2314 kb/s
  
      Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s
  
      Metadata:
  
        creation_time   : 2010-02-09 19:11:10
  
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
  
      Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 2186 kb/s, 30 fps, 30 tbr, 30k tbn, 60 tbc
  
      Metadata:
  
        creation_time   : 2010-02-09 19:11:10
  
        handler_name    : (C) 2007 Google Inc. v08.13.2007.
  
  Output #0, flv, to 'output_file.flv':
  
      Stream #0:0: Video: flv1, yuv420p, 1280x720, q=2-31, 150 kb/s, 90k tbn, 30 tbc
  
  encoded frame #0
  
  encoded frame #1
  
  encoded frame #2
  
  encoded frame #3
  
  .
  
  .
  
  .
  
  encoded frame #8142
  
  encoded frame #8143
  
  encoded frame #8144
  
  encoded frame #8145

  I noticed that the bitrate is honored as long as the container is a mp4, mov, f4v, or something similar. If I try flv, wmv, or other different containers, then the bitrate is not honored. Also, the bitrate that is automatically set for wmv is different from that of flv. I am not sure what I am doing wrong. I suspect it has to do with the pts, however, I cannot find a solution :(.