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• Cropping Square Video using FFmpeg

  27 juin 2014, par zoruc

  Updated

  So I am trying to decode a mp4 file, crop the video into a square, and then re encode it back out to another mp4 file. This is my current code but there are a few issues with it.

  One is that the video doesn’t keep its rotation after the video has been re encoded

  Second is that the frames get outputted in a very fast video file that is not the same length as the original

  Third is that there is no sound

  Lastly and most importantly is do I need AVFilter to do the frame cropping or can it just be done per frame as a resize of the frame and then encoded back out.

  const char *inputPath = "test.mp4";
  
  const char *outPath = "cropped.mp4";
  
  const char *outFileType = "mp4";
  
  
  
  static AVFrame *oframe = NULL; 
  
  static AVFilterGraph *filterGraph = NULL;  
  
  static AVFilterContext *crop_ctx = NULL;
  
  static AVFilterContext *buffersink_ctx = NULL;
  
  static AVFilterContext *buffer_ctx = NULL;
  
  
  
  int err;
  
  
  
  int crop_video(int width, int height) {
  
  
  
  av_register_all();
  
  avcodec_register_all();
  
  avfilter_register_all();
  
  
  
  AVFormatContext *inCtx = NULL;
  
  
  
  // open input file
  
  err = avformat_open_input(&inCtx, inputPath, NULL, NULL);
  
  if (err < 0) {
  
      printf("error at open input in\n");
  
      return err;
  
  }
  
  
  
  // get input file stream info
  
  err = avformat_find_stream_info(inCtx, NULL);
  
  if (err < 0) {
  
      printf("error at find stream info\n");
  
      return err;
  
  }
  
  
  
  // get info about video
  
  av_dump_format(inCtx, 0, inputPath, 0);
  
  
  
  // find video input stream
  
  int vs = -1;
  
  int s;
  
  for (s = 0; s < inCtx->nb_streams; ++s) {
  
      if (inCtx->streams[s] && inCtx->streams[s]->codec && inCtx->streams[s]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          vs = s;
  
          break;
  
      }
  
  }
  
  
  
  // check if video stream is valid
  
  if (vs == -1) {
  
      printf("error at open video stream\n");
  
      return -1;
  
  }
  
  
  
  // set output format
  
  AVOutputFormat * outFmt = av_guess_format(outFileType, NULL, NULL);
  
  if (!outFmt) {
  
      printf("error at output format\n");
  
      return -1;
  
  }
  
  
  
  // get an output context to write to
  
  AVFormatContext *outCtx = NULL;
  
  err = avformat_alloc_output_context2(&outCtx, outFmt, NULL, NULL);
  
  if (err < 0 || !outCtx) {
  
      printf("error at output context\n");
  
      return err;
  
  }
  
  
  
  // input and output stream
  
  AVStream *outStrm = avformat_new_stream(outCtx, NULL);
  
  AVStream *inStrm = inCtx->streams[vs];
  
  
  
  // add a new codec for the output stream
  
  AVCodec *codec = NULL;
  
  avcodec_get_context_defaults3(outStrm->codec, codec);
  
  
  
  outStrm->codec->thread_count = 1;
  
  
  
  outStrm->codec->coder_type = AVMEDIA_TYPE_VIDEO;
  
  
  
  if(outCtx->oformat->flags & AVFMT_GLOBALHEADER) {
  
      outStrm->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  }
  
  
  
  outStrm->codec->sample_aspect_ratio = outStrm->sample_aspect_ratio = inStrm->sample_aspect_ratio;
  
  
  
  err = avio_open(&outCtx->pb, outPath, AVIO_FLAG_WRITE);
  
  if (err < 0) {
  
      printf("error at opening outpath\n");
  
      return err;
  
  }
  
  
  
  outStrm->disposition = inStrm->disposition;
  
  outStrm->codec->bits_per_raw_sample = inStrm->codec->bits_per_raw_sample;
  
  outStrm->codec->chroma_sample_location = inStrm->codec->chroma_sample_location;
  
  outStrm->codec->codec_id = inStrm->codec->codec_id;
  
  outStrm->codec->codec_type = inStrm->codec->codec_type;
  
  
  
  if (!outStrm->codec->codec_tag) {
  
      if (! outCtx->oformat->codec_tag
  
          || av_codec_get_id (outCtx->oformat->codec_tag, inStrm->codec->codec_tag) == outStrm->codec->codec_id
  
          || av_codec_get_tag(outCtx->oformat->codec_tag, inStrm->codec->codec_id) <= 0) {
  
          outStrm->codec->codec_tag = inStrm->codec->codec_tag;
  
      }
  
  }
  
  
  
  outStrm->codec->bit_rate = inStrm->codec->bit_rate;
  
  outStrm->codec->rc_max_rate = inStrm->codec->rc_max_rate;
  
  outStrm->codec->rc_buffer_size = inStrm->codec->rc_buffer_size;
  
  
  
  const size_t extra_size_alloc = (inStrm->codec->extradata_size > 0) ?
  
  (inStrm->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE) :
  
  0;
  
  
  
  if (extra_size_alloc) {
  
      outStrm->codec->extradata = (uint8_t*)av_mallocz(extra_size_alloc);
  
      memcpy( outStrm->codec->extradata, inStrm->codec->extradata, inStrm->codec->extradata_size);
  
  }
  
  
  
  outStrm->codec->extradata_size = inStrm->codec->extradata_size;
  
  
  
  AVRational input_time_base = inStrm->time_base;
  
  AVRational frameRate = {25, 1};
  
  if (inStrm->r_frame_rate.num && inStrm->r_frame_rate.den
  
      && (1.0 * inStrm->r_frame_rate.num / inStrm->r_frame_rate.den < 1000.0)) {
  
      frameRate.num = inStrm->r_frame_rate.num;
  
      frameRate.den = inStrm->r_frame_rate.den;
  
  }
  
  
  
  outStrm->r_frame_rate = frameRate;
  
  outStrm->codec->time_base = inStrm->codec->time_base;
  
  
  
  outStrm->codec->pix_fmt = inStrm->codec->pix_fmt;
  
  outStrm->codec->width = width;
  
  outStrm->codec->height =  height;
  
  outStrm->codec->has_b_frames =  inStrm->codec->has_b_frames;
  
  
  
  if (!outStrm->codec->sample_aspect_ratio.num) {
  
      AVRational r0 = {0, 1};
  
      outStrm->codec->sample_aspect_ratio =
  
      outStrm->sample_aspect_ratio =
  
      inStrm->sample_aspect_ratio.num ? inStrm->sample_aspect_ratio :
  
      inStrm->codec->sample_aspect_ratio.num ?
  
      inStrm->codec->sample_aspect_ratio : r0;
  
  }
  
  
  
  avformat_write_header(outCtx, NULL);
  
  
  
  filterGraph = avfilter_graph_alloc();
  
  if (!filterGraph) {
  
      printf("could not open filter graph");
  
      return -1;
  
  }
  
  
  
  AVFilter *crop = avfilter_get_by_name("crop");
  
  AVFilter *buffer = avfilter_get_by_name("buffer");
  
  AVFilter *buffersink = avfilter_get_by_name("buffersink");
  
  
  
  char args[512];
  
  
  
  snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
           width, height, inStrm->codec->pix_fmt,
  
           inStrm->codec->time_base.num, inStrm->codec->time_base.den,
  
           inStrm->codec->sample_aspect_ratio.num, inStrm->codec->sample_aspect_ratio.den);
  
  
  
  err = avfilter_graph_create_filter(&buffer_ctx, buffer, NULL, args, NULL, filterGraph);
  
  if (err < 0) {
  
      printf("error initializing buffer filter\n");
  
      return err;
  
  }
  
  
  
  err = avfilter_graph_create_filter(&buffersink_ctx, buffersink, NULL, NULL, NULL, filterGraph);
  
  if (err < 0) {
  
      printf("unable to create buffersink filter\n");
  
      return err;
  
  }
  
  snprintf(args, sizeof(args), "%d:%d", width, height);
  
  err = avfilter_graph_create_filter(&crop_ctx, crop, NULL, args, NULL, filterGraph);
  
  if (err < 0) {
  
      printf("error initializing crop filter\n");
  
      return err;
  
  }
  
  
  
  err = avfilter_link(buffer_ctx, 0, crop_ctx, 0);
  
  if (err < 0) {
  
      printf("error linking filters\n");
  
      return err;
  
  }
  
  
  
  err = avfilter_link(crop_ctx, 0, buffersink_ctx, 0);
  
  if (err < 0) {
  
      printf("error linking filters\n");
  
      return err;
  
  }
  
  
  
  err = avfilter_graph_config(filterGraph, NULL);
  
  if (err < 0) {
  
      printf("error configuring the filter graph\n");
  
      return err;
  
  }
  
  
  
  printf("filtergraph configured\n");
  
  
  
  for (;;) {
  
  
  
      AVPacket packet = {0};
  
      av_init_packet(&packet);
  
  
  
      err = AVERROR(EAGAIN);
  
      while (AVERROR(EAGAIN) == err)
  
          err = av_read_frame(inCtx, &packet);
  
  
  
      if (err < 0) {
  
          if (AVERROR_EOF != err && AVERROR(EIO) != err) {
  
              printf("eof error\n");
  
              return 1;
  
          } else {
  
              break;
  
          }
  
      }
  
  
  
      if (packet.stream_index == vs) {
  
  
  
          //
  
          //            AVPacket pkt_temp_;
  
          //            memset(&pkt_temp_, 0, sizeof(pkt_temp_));
  
          //            AVPacket *pkt_temp = &pkt_temp_;
  
          //
  
          //            *pkt_temp = packet;
  
          //
  
          //            int error, got_frame;
  
          //            int new_packet = 1;
  
          //
  
          //            error = avcodec_decode_video2(inStrm->codec, frame, &got_frame, pkt_temp);
  
          //            if(error < 0) {
  
          //                LOGE("error %d", error);
  
          //            }
  
          //
  
          //            // if (error >= 0) {
  
          //
  
          //            // push the video data from decoded frame into the filtergraph
  
          //            int err = av_buffersrc_write_frame(buffer_ctx, frame);
  
          //            if (err < 0) {
  
          //                LOGE("error writing frame to buffersrc");
  
          //                return -1;
  
          //            }
  
          //            // pull filtered video from the filtergraph
  
          //            for (;;) {
  
          //                int err = av_buffersink_get_frame(buffersink_ctx, oframe);
  
          //                if (err == AVERROR_EOF || err == AVERROR(EAGAIN))
  
          //                    break;
  
          //                if (err < 0) {
  
          //                    LOGE("error reading buffer from buffersink");
  
          //                    return -1;
  
          //                }
  
          //            }
  
          //
  
          //            LOGI("output frame");
  
  
  
          err = av_interleaved_write_frame(outCtx, &packet);
  
          if (err < 0) {
  
              printf("error at write frame");
  
              return -1;
  
          }
  
  
  
          //}
  
      }
  
  
  
      av_free_packet(&packet);
  
  }
  
  
  
  av_write_trailer(outCtx);
  
  if (!(outCtx->oformat->flags & AVFMT_NOFILE) && outCtx->pb)
  
      avio_close(outCtx->pb);
  
  
  
  avformat_free_context(outCtx);
  
  avformat_close_input(&inCtx);
  
  
  
  return 0;

  }

• lavf : switch to AVStream.time_base as the hint for the muxer timebase

  18 mai 2014, par Anton Khirnov

  lavf : switch to AVStream.time_base as the hint for the muxer timebase
  Previously, AVStream.codec.time_base was used for that purpose, which
  
  was quite confusing for the callers. This change also opens the path for
  
  removing AVStream.codec.
  The change in the lavf-mkv test is due to the native timebase (1/1000)
  
  being used instead of the default one (1/90000), so the packets are now
  
  sent to the crc muxer in the same order in which they are demuxed
  
  (previously some of them got reordered because of inexact timestamp
  
  conversion).
  

  • [DH] doc/APIchanges
  • [DH] libavformat/avformat.h
  • [DH] libavformat/avienc.c
  • [DH] libavformat/filmstripenc.c
  • [DH] libavformat/framehash.c
  • [DH] libavformat/movenc.c
  • [DH] libavformat/mpegtsenc.c
  • [DH] libavformat/mux.c
  • [DH] libavformat/mxfenc.c
  • [DH] libavformat/oggenc.c
  • [DH] libavformat/riffenc.c
  • [DH] libavformat/rmenc.c
  • [DH] libavformat/swf.h
  • [DH] libavformat/swfenc.c
  • [DH] libavformat/utils.c
  • [DH] libavformat/version.h
  • [DH] libavformat/yuv4mpegenc.c
  • [DH] tests/ref/lavf/mkv

• lavf : switch to AVStream.time_base as the hint for the muxer timebase

  18 mai 2014, par Anton Khirnov

  lavf : switch to AVStream.time_base as the hint for the muxer timebase
  Previously, AVStream.codec.time_base was used for that purpose, which
  
  was quite confusing for the callers. This change also opens the path for
  
  removing AVStream.codec.
  The change in the lavf-mkv test is due to the native timebase (1/1000)
  
  being used instead of the default one (1/90000), so the packets are now
  
  sent to the crc muxer in the same order in which they are demuxed
  
  (previously some of them got reordered because of inexact timestamp
  
  conversion).
  

  • [DBH] doc/APIchanges
  • [DBH] libavformat/avformat.h
  • [DBH] libavformat/avienc.c
  • [DBH] libavformat/filmstripenc.c
  • [DBH] libavformat/framehash.c
  • [DBH] libavformat/movenc.c
  • [DBH] libavformat/mpegtsenc.c
  • [DBH] libavformat/mux.c
  • [DBH] libavformat/mxfenc.c
  • [DBH] libavformat/oggenc.c
  • [DBH] libavformat/riffenc.c
  • [DBH] libavformat/rmenc.c
  • [DBH] libavformat/swf.h
  • [DBH] libavformat/swfenc.c
  • [DBH] libavformat/utils.c
  • [DBH] libavformat/version.h
  • [DBH] libavformat/yuv4mpegenc.c
  • [DBH] tests/ref/lavf/mkv