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• Scale filter crashes with error when used from transcoding example

  27 juin 2017, par Vali

  I’ve modified a bit (just to compile in c++) this code example :
  https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/transcoding.c.

  What works : as is (null filter), a number of other filters like framerate, drawtext, ...

  What doesn’t work : scale filter when scaling down.

  I use the following syntax for scale ( I’ve tried many others also, same effect) :
  "scale=w=iw/2 :-1"

  The error is : "Input picture width (240) is greater than stride (128)" where the values for width and stride depend on the input.

  Misc environment info : windows, VS 2017, input example : rtsp ://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mov

  Any clue as to what I’m doing wrong ?

  Thanks !

  ---

  EDITED to add working code sample

  ---

  #pragma comment(lib, "avcodec.lib")
  
  #pragma comment(lib, "avutil.lib")
  
  #pragma comment(lib, "avformat.lib")
  
  #pragma comment(lib, "avfilter.lib")
  
  
  
  /*
  
  * Copyright (c) 2010 Nicolas George
  
  * Copyright (c) 2011 Stefano Sabatini
  
  * Copyright (c) 2014 Andrey Utkin
  
  *
  
  **** EDITED 2017 for testing (see original here: https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/transcoding.c)
  
  *
  
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  
  * of this software and associated documentation files (the "Software"), to deal
  
  * in the Software without restriction, including without limitation the rights
  
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  
  * copies of the Software, and to permit persons to whom the Software is
  
  * furnished to do so, subject to the following conditions:
  
  *
  
  * The above copyright notice and this permission notice shall be included in
  
  * all copies or substantial portions of the Software.
  
  *
  
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  
  * THE SOFTWARE.
  
  */
  
  
  
  /**
  
  * @file
  
  * API example for demuxing, decoding, filtering, encoding and muxing
  
  * @example transcoding.c
  
  */
  
  
  
  extern "C"
  
  {
  
      #include <libavcodec></libavcodec>avcodec.h>
  
      #include <libavformat></libavformat>avformat.h>
  
      #include <libavfilter></libavfilter>avfiltergraph.h>
  
      #include <libavfilter></libavfilter>buffersink.h>
  
      #include <libavfilter></libavfilter>buffersrc.h>
  
      #include <libavutil></libavutil>opt.h>
  
      #include <libavutil></libavutil>pixdesc.h>
  
  }
  
  
  
  
  
  static AVFormatContext *ifmt_ctx;
  
  static AVFormatContext *ofmt_ctx;
  
  typedef struct FilteringContext {
  
      AVFilterContext *buffersink_ctx;
  
      AVFilterContext *buffersrc_ctx;
  
      AVFilterGraph *filter_graph;
  
  } FilteringContext;
  
  static FilteringContext *filter_ctx;
  
  
  
  typedef struct StreamContext {
  
      AVCodecContext *dec_ctx;
  
      AVCodecContext *enc_ctx;
  
  } StreamContext;
  
  static StreamContext *stream_ctx;
  
  
  
  static int open_input_file(const char *filename, int&amp; videoStreamIndex)
  
  {
  
      int ret;
  
      unsigned int i;
  
  
  
      ifmt_ctx = NULL;
  
      if ((ret = avformat_open_input(&amp;ifmt_ctx, filename, NULL, NULL)) &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  
          return ret;
  
      }
  
  
  
      if ((ret = avformat_find_stream_info(ifmt_ctx, NULL)) &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  
          return ret;
  
      }
  
  
  
      // Just need video
  
      videoStreamIndex = -1;
  
      for (unsigned int i = 0; i &lt; ifmt_ctx->nb_streams; i++)
  
      {
  
          if (ifmt_ctx->streams[i]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO)
  
              continue;
  
          videoStreamIndex = i;
  
          break;
  
      }
  
      if (videoStreamIndex &lt; 0)
  
      {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find video stream\n");
  
          return videoStreamIndex;
  
      }
  
  
  
  
  
      stream_ctx = (StreamContext*)av_mallocz_array(ifmt_ctx->nb_streams, sizeof(*stream_ctx));
  
      if (!stream_ctx)
  
          return AVERROR(ENOMEM);
  
  
  
      for (i = 0; i &lt; ifmt_ctx->nb_streams; i++) {
  
  
  
          // Just need video
  
          if (i != videoStreamIndex)
  
              continue;
  
  
  
  
  
          AVStream *stream = ifmt_ctx->streams[i];
  
          AVCodec *dec = avcodec_find_decoder(stream->codecpar->codec_id);
  
          AVCodecContext *codec_ctx;
  
          if (!dec) {
  
              av_log(NULL, AV_LOG_ERROR, "Failed to find decoder for stream #%u\n", i);
  
              return AVERROR_DECODER_NOT_FOUND;
  
          }
  
          codec_ctx = avcodec_alloc_context3(dec);
  
          if (!codec_ctx) {
  
              av_log(NULL, AV_LOG_ERROR, "Failed to allocate the decoder context for stream #%u\n", i);
  
              return AVERROR(ENOMEM);
  
          }
  
          ret = avcodec_parameters_to_context(codec_ctx, stream->codecpar);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Failed to copy decoder parameters to input decoder context "
  
                  "for stream #%u\n", i);
  
              return ret;
  
          }
  
          /* Reencode video &amp; audio and remux subtitles etc. */
  
          if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO
  
              || codec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
              if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
  
                  codec_ctx->framerate = av_guess_frame_rate(ifmt_ctx, stream, NULL);
  
              /* Open decoder */
  
              ret = avcodec_open2(codec_ctx, dec, NULL);
  
              if (ret &lt; 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Failed to open decoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
          }
  
          stream_ctx[i].dec_ctx = codec_ctx;
  
      }
  
  
  
      av_dump_format(ifmt_ctx, 0, filename, 0);
  
      return 0;
  
  }
  
  
  
  static int open_output_file(const char *filename, const int videoStreamIndex)
  
  {
  
      AVStream *out_stream;
  
      AVStream *in_stream;
  
      AVCodecContext *dec_ctx, *enc_ctx;
  
      AVCodec *encoder;
  
      int ret;
  
      unsigned int i;
  
  
  
      ofmt_ctx = NULL;
  
      avformat_alloc_output_context2(&amp;ofmt_ctx, NULL, NULL, filename);
  
      if (!ofmt_ctx) {
  
          av_log(NULL, AV_LOG_ERROR, "Could not create output context\n");
  
          return AVERROR_UNKNOWN;
  
      }
  
  
  
  
  
      for (i = 0; i &lt; ifmt_ctx->nb_streams; i++) {
  
          // Just need video
  
          if (i != videoStreamIndex)
  
              continue;
  
  
  
          out_stream = avformat_new_stream(ofmt_ctx, NULL);
  
          if (!out_stream) {
  
              av_log(NULL, AV_LOG_ERROR, "Failed allocating output stream\n");
  
              return AVERROR_UNKNOWN;
  
          }
  
  
  
          in_stream = ifmt_ctx->streams[i];
  
          dec_ctx = stream_ctx[i].dec_ctx;
  
  
  
          if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
  
              /* in this example, we choose transcoding to same codec */
  
              encoder = avcodec_find_encoder(dec_ctx->codec_id);
  
              if (!encoder) {
  
                  av_log(NULL, AV_LOG_FATAL, "Necessary encoder not found\n");
  
                  return AVERROR_INVALIDDATA;
  
              }
  
              enc_ctx = avcodec_alloc_context3(encoder);
  
              if (!enc_ctx) {
  
                  av_log(NULL, AV_LOG_FATAL, "Failed to allocate the encoder context\n");
  
                  return AVERROR(ENOMEM);
  
              }
  
  
  
              /* In this example, we transcode to same properties (picture size,
  
              * sample rate etc.). These properties can be changed for output
  
              * streams easily using filters */
  
              enc_ctx->height = dec_ctx->height;
  
              enc_ctx->width = dec_ctx->width;
  
              enc_ctx->sample_aspect_ratio = dec_ctx->sample_aspect_ratio;
  
              /* take first format from list of supported formats */
  
              if (encoder->pix_fmts)
  
                  enc_ctx->pix_fmt = encoder->pix_fmts[0];
  
              else
  
                  enc_ctx->pix_fmt = dec_ctx->pix_fmt;
  
  
  
              /* video time_base can be set to whatever is handy and supported by encoder */
  
              //enc_ctx->time_base = av_inv_q(dec_ctx->framerate);
  
              enc_ctx->time_base = dec_ctx->time_base;
  
  
  
  
  
              /* Third parameter can be used to pass settings to encoder */
  
              ret = avcodec_open2(enc_ctx, encoder, NULL);
  
              if (ret &lt; 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
              ret = avcodec_parameters_from_context(out_stream->codecpar, enc_ctx);
  
              if (ret &lt; 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Failed to copy encoder parameters to output stream #%u\n", i);
  
                  return ret;
  
              }
  
              if (ofmt_ctx->oformat->flags &amp; AVFMT_GLOBALHEADER)
  
                  enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  
  
              out_stream->time_base = enc_ctx->time_base;
  
              stream_ctx[i].enc_ctx = enc_ctx;
  
          }
  
          else if (dec_ctx->codec_type == AVMEDIA_TYPE_UNKNOWN) {
  
              av_log(NULL, AV_LOG_FATAL, "Elementary stream #%d is of unknown type, cannot proceed\n", i);
  
              return AVERROR_INVALIDDATA;
  
          }
  
          else {
  
              /* if this stream must be remuxed */
  
              ret = avcodec_parameters_copy(out_stream->codecpar, in_stream->codecpar);
  
              if (ret &lt; 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Copying parameters for stream #%u failed\n", i);
  
                  return ret;
  
              }
  
              out_stream->time_base = in_stream->time_base;
  
          }
  
  
  
      }
  
      av_dump_format(ofmt_ctx, 0, filename, 1);
  
  
  
      if (!(ofmt_ctx->oformat->flags &amp; AVFMT_NOFILE)) {
  
          ret = avio_open(&amp;ofmt_ctx->pb, filename, AVIO_FLAG_WRITE);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Could not open output file '%s'", filename);
  
              return ret;
  
          }
  
      }
  
  
  
      /* init muxer, write output file header */
  
      ret = avformat_write_header(ofmt_ctx, NULL);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Error occurred when opening output file\n");
  
          return ret;
  
      }
  
  
  
      return 0;
  
  }
  
  
  
  static int init_filter(FilteringContext* fctx, AVCodecContext *dec_ctx,
  
      AVCodecContext *enc_ctx, const char *filter_spec)
  
  {
  
      char args[512];
  
      int ret = 0;
  
      AVFilter *buffersrc = NULL;
  
      AVFilter *buffersink = NULL;
  
      AVFilterContext *buffersrc_ctx = NULL;
  
      AVFilterContext *buffersink_ctx = NULL;
  
      AVFilterInOut *outputs = avfilter_inout_alloc();
  
      AVFilterInOut *inputs = avfilter_inout_alloc();
  
      AVFilterGraph *filter_graph = avfilter_graph_alloc();
  
  
  
      if (!outputs || !inputs || !filter_graph) {
  
          ret = AVERROR(ENOMEM);
  
          goto end;
  
      }
  
  
  
      if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          buffersrc = avfilter_get_by_name("buffer");
  
          buffersink = avfilter_get_by_name("buffersink");
  
          if (!buffersrc || !buffersink) {
  
              av_log(NULL, AV_LOG_ERROR, "filtering source or sink element not found\n");
  
              ret = AVERROR_UNKNOWN;
  
              goto end;
  
          }
  
  
  
          snprintf(args, sizeof(args),
  
              "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
              dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  
              dec_ctx->time_base.num, dec_ctx->time_base.den,
  
              dec_ctx->sample_aspect_ratio.num,
  
              dec_ctx->sample_aspect_ratio.den);
  
  
  
          ret = avfilter_graph_create_filter(&amp;buffersrc_ctx, buffersrc, "in",
  
              args, NULL, filter_graph);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  
              goto end;
  
          }
  
  
  
          ret = avfilter_graph_create_filter(&amp;buffersink_ctx, buffersink, "out",
  
              NULL, NULL, filter_graph);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  
              goto end;
  
          }
  
  
  
          ret = av_opt_set_bin(buffersink_ctx, "pix_fmts",
  
              (uint8_t*)&amp;enc_ctx->pix_fmt, sizeof(enc_ctx->pix_fmt),
  
              AV_OPT_SEARCH_CHILDREN);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
  
              goto end;
  
          }
  
      }
  
      else {
  
          ret = AVERROR_UNKNOWN;
  
          goto end;
  
      }
  
  
  
      /* Endpoints for the filter graph. */
  
      outputs->name = av_strdup("in");
  
      outputs->filter_ctx = buffersrc_ctx;
  
      outputs->pad_idx = 0;
  
      outputs->next = NULL;
  
  
  
      inputs->name = av_strdup("out");
  
      inputs->filter_ctx = buffersink_ctx;
  
      inputs->pad_idx = 0;
  
      inputs->next = NULL;
  
  
  
      if (!outputs->name || !inputs->name) {
  
          ret = AVERROR(ENOMEM);
  
          goto end;
  
      }
  
  
  
      if ((ret = avfilter_graph_parse_ptr(filter_graph, filter_spec,
  
          &amp;inputs, &amp;outputs, NULL)) &lt; 0)
  
          goto end;
  
  
  
      if ((ret = avfilter_graph_config(filter_graph, NULL)) &lt; 0)
  
          goto end;
  
  
  
      /* Fill FilteringContext */
  
      fctx->buffersrc_ctx = buffersrc_ctx;
  
      fctx->buffersink_ctx = buffersink_ctx;
  
      fctx->filter_graph = filter_graph;
  
  
  
  end:
  
      avfilter_inout_free(&amp;inputs);
  
      avfilter_inout_free(&amp;outputs);
  
  
  
      return ret;
  
  }
  
  
  
  static int init_filters(const int videoStreamIndex)
  
  {
  
      const char *filter_spec;
  
      unsigned int i;
  
      int ret;
  
      filter_ctx = (FilteringContext*)av_malloc_array(ifmt_ctx->nb_streams, sizeof(*filter_ctx));
  
      if (!filter_ctx)
  
          return AVERROR(ENOMEM);
  
  
  
      for (i = 0; i &lt; ifmt_ctx->nb_streams; i++) {
  
  
  
          // Just video
  
          if (i != videoStreamIndex)
  
              continue;
  
  
  
          filter_ctx[i].buffersrc_ctx = NULL;
  
          filter_ctx[i].buffersink_ctx = NULL;
  
          filter_ctx[i].filter_graph = NULL;
  
          if (!(ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO
  
              || ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO))
  
              continue;
  
  
  
          filter_spec = "null"; /* passthrough (dummy) filter for video */
  
          //filter_spec = "scale=w=iw/2:-1";
  
          // filter_spec = "drawtext=fontfile=FreeSerif.ttf: text='%{localtime}': x=w-text_w: y=0: fontsize=24: fontcolor=yellow@1.0: box=1: boxcolor=red@1.0";
  
          // filter_spec = "drawtext=fontfile=FreeSerif.ttf :text='test': x=w-text_w: y=text_h: fontsize=24: fontcolor=yellow@1.0: box=1: boxcolor=red@1.0";
  
  
  
          ret = init_filter(&amp;filter_ctx[i], stream_ctx[i].dec_ctx,
  
              stream_ctx[i].enc_ctx, filter_spec);
  
          if (ret)
  
              return ret;
  
      }
  
      return 0;
  
  }
  
  
  
  static int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, int *got_frame, const int videoStreamIndex) {
  
  
  
      // Just video
  
      if (stream_index != videoStreamIndex)
  
          return 0;
  
  
  
      int ret;
  
      int got_frame_local;
  
      AVPacket enc_pkt;
  
      int(*enc_func)(AVCodecContext *, AVPacket *, const AVFrame *, int *) =
  
          (ifmt_ctx->streams[stream_index]->codecpar->codec_type ==
  
              AVMEDIA_TYPE_VIDEO) ? avcodec_encode_video2 : avcodec_encode_audio2;
  
  
  
      if (!got_frame)
  
          got_frame = &amp;got_frame_local;
  
  
  
      // av_log(NULL, AV_LOG_INFO, "Encoding frame\n");
  
      /* encode filtered frame */
  
      enc_pkt.data = NULL;
  
      enc_pkt.size = 0;
  
      av_init_packet(&amp;enc_pkt);
  
  
  
      ret = enc_func(stream_ctx[stream_index].enc_ctx, &amp;enc_pkt,
  
          filt_frame, got_frame);
  
  
  
      av_frame_free(&amp;filt_frame);
  
      if (ret &lt; 0)
  
          return ret;
  
      if (!(*got_frame))
  
          return 0;
  
  
  
      /* prepare packet for muxing */
  
      /*enc_pkt.stream_index = stream_index;
  
      av_packet_rescale_ts(&amp;enc_pkt, stream_ctx[stream_index].enc_ctx->time_base, ofmt_ctx->streams[stream_index]->time_base);*/
  
      enc_pkt.stream_index = 0;
  
      av_packet_rescale_ts(&amp;enc_pkt, stream_ctx[stream_index].enc_ctx->time_base, ofmt_ctx->streams[0]->time_base);
  
  
  
      av_log(NULL, AV_LOG_DEBUG, "Muxing frame\n");
  
      /* mux encoded frame */
  
      ret = av_interleaved_write_frame(ofmt_ctx, &amp;enc_pkt);
  
      return ret;
  
  }
  
  
  
  static int filter_encode_write_frame(AVFrame *frame, unsigned int stream_index, const int videoStreamIndex)
  
  {
  
      // Just video, all else crashes
  
      if (stream_index != videoStreamIndex)
  
          return 0;
  
  
  
      int ret;
  
      AVFrame *filt_frame;
  
  
  
      // av_log(NULL, AV_LOG_INFO, "Pushing decoded frame to filters\n");
  
      /* push the decoded frame into the filtergraph */
  
      ret = av_buffersrc_add_frame_flags(filter_ctx[stream_index].buffersrc_ctx,
  
          frame, 0);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  
          return ret;
  
      }
  
  
  
      /* pull filtered frames from the filtergraph */
  
      while (1) {
  
          filt_frame = av_frame_alloc();
  
          if (!filt_frame) {
  
              ret = AVERROR(ENOMEM);
  
              break;
  
          }
  
          // av_log(NULL, AV_LOG_INFO, "Pulling filtered frame from filters\n");
  
          ret = av_buffersink_get_frame(filter_ctx[stream_index].buffersink_ctx,
  
              filt_frame);
  
          if (ret &lt; 0) {
  
              /* if no more frames for output - returns AVERROR(EAGAIN)
  
              * if flushed and no more frames for output - returns AVERROR_EOF
  
              * rewrite retcode to 0 to show it as normal procedure completion
  
              */
  
              if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  
                  ret = 0;
  
              av_frame_free(&amp;filt_frame);
  
              break;
  
          }
  
  
  
          filt_frame->pict_type = AV_PICTURE_TYPE_NONE;
  
          ret = encode_write_frame(filt_frame, stream_index, NULL, videoStreamIndex);
  
          if (ret &lt; 0)
  
              break;
  
      }
  
  
  
      return ret;
  
  }
  
  
  
  static int flush_encoder(unsigned int stream_index, const int videoStreamIndex)
  
  {
  
      int ret;
  
      int got_frame;
  
  
  
      // Just video
  
      if (stream_index != videoStreamIndex)
  
          return 0;
  
  
  
      if (!(stream_ctx[stream_index].enc_ctx->codec->capabilities &amp;
  
          AV_CODEC_CAP_DELAY))
  
          return 0;
  
  
  
      while (1) {
  
          av_log(NULL, AV_LOG_INFO, "Flushing stream #%u encoder\n", stream_index);
  
          ret = encode_write_frame(NULL, stream_index, &amp;got_frame, videoStreamIndex);
  
          if (ret &lt; 0)
  
              break;
  
          if (!got_frame)
  
              return 0;
  
      }
  
      return ret;
  
  }
  
  
  
  
  
  #include <vector>
  
  
  
  int main(int argc, char **argv)
  
  {
  
      int ret;
  
  
  
      AVPacket packet;
  
      packet.data = NULL;
  
      packet.size = 0;
  
  
  
      AVFrame *frame = NULL;
  
      enum AVMediaType type;
  
      unsigned int stream_index;
  
      unsigned int i;
  
      int got_frame;
  
      int(*dec_func)(AVCodecContext *, AVFrame *, int *, const AVPacket *);
  
  
  
  
  
  #ifdef _DEBUG
  
      // Hardcoded arguments
  
      std::vector varguments;
  
      {
  
          varguments.push_back(argv[0]);
  
  
  
          // Source
  
          varguments.push_back("./big_buck_bunny_short.mp4 ");
  
  
  
          // Destination
  
          varguments.push_back("./big_buck_bunny_short-processed.mp4");
  
      }
  
  
  
      char** arguments = new char*[varguments.size()];
  
      for (unsigned int i = 0; i &lt; varguments.size(); i++)
  
      {
  
          arguments[i] = varguments[i];
  
      }
  
      argc = varguments.size();
  
      argv = arguments;
  
  #endif // _DEBUG
  
  
  
  
  
      if (argc != 3) {
  
          av_log(NULL, AV_LOG_ERROR, "Usage: %s <input file="file" /> <output file="file">\n", argv[0]);
  
          return 1;
  
      }
  
  
  
      av_register_all();
  
      avfilter_register_all();
  
  
  
      int videoStreamIndex = -1;
  
      if ((ret = open_input_file(argv[1], videoStreamIndex)) &lt; 0)
  
          goto end;
  
      if ((ret = open_output_file(argv[2], videoStreamIndex)) &lt; 0)
  
          goto end;
  
      if ((ret = init_filters(videoStreamIndex)) &lt; 0)
  
          goto end;
  
  
  
      // Stop after a couple of frames
  
      int framesToGet = 100;
  
  
  
      /* read all packets */
  
      //while (framesToGet--)
  
      while(1)
  
      {
  
          if ((ret = av_read_frame(ifmt_ctx, &amp;packet)) &lt; 0)
  
              break;
  
          stream_index = packet.stream_index;
  
  
  
          // I just need video
  
          if (stream_index != videoStreamIndex) {
  
              av_packet_unref(&amp;packet);
  
              continue;
  
          }
  
  
  
          type = ifmt_ctx->streams[packet.stream_index]->codecpar->codec_type;
  
          av_log(NULL, AV_LOG_DEBUG, "Demuxer gave frame of stream_index %u\n",
  
              stream_index);
  
  
  
          if (filter_ctx[stream_index].filter_graph) {
  
              av_log(NULL, AV_LOG_DEBUG, "Going to reencode&amp;filter the frame\n");
  
              frame = av_frame_alloc();
  
              if (!frame) {
  
                  ret = AVERROR(ENOMEM);
  
                  break;
  
              }
  
              av_packet_rescale_ts(&amp;packet,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  stream_ctx[stream_index].dec_ctx->time_base);
  
              dec_func = (type == AVMEDIA_TYPE_VIDEO) ? avcodec_decode_video2 :
  
                  avcodec_decode_audio4;
  
              ret = dec_func(stream_ctx[stream_index].dec_ctx, frame,
  
                  &amp;got_frame, &amp;packet);
  
              if (ret &lt; 0) {
  
                  av_frame_free(&amp;frame);
  
                  av_log(NULL, AV_LOG_ERROR, "Decoding failed\n");
  
                  break;
  
              }
  
  
  
              if (got_frame) {
  
                  frame->pts = frame->best_effort_timestamp;
  
                  ret = filter_encode_write_frame(frame, stream_index, videoStreamIndex);
  
                  av_frame_free(&amp;frame);
  
                  if (ret &lt; 0)
  
                      goto end;
  
              }
  
              else {
  
                  av_frame_free(&amp;frame);
  
              }
  
          }
  
          else {
  
              /* remux this frame without reencoding */
  
              av_packet_rescale_ts(&amp;packet,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  ofmt_ctx->streams[stream_index]->time_base);
  
  
  
              ret = av_interleaved_write_frame(ofmt_ctx, &amp;packet);
  
              if (ret &lt; 0)
  
                  goto end;
  
          }
  
          av_packet_unref(&amp;packet);
  
      }
  
  
  
      /* flush filters and encoders */
  
      for (i = 0; i &lt; ifmt_ctx->nb_streams; i++) {
  
          /* flush filter */
  
          if (!filter_ctx[i].filter_graph)
  
              continue;
  
          ret = filter_encode_write_frame(NULL, i, videoStreamIndex);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Flushing filter failed\n");
  
              goto end;
  
          }
  
  
  
          /* flush encoder */
  
          ret = flush_encoder(i, videoStreamIndex);
  
          if (ret &lt; 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Flushing encoder failed\n");
  
              goto end;
  
          }
  
      }
  
  
  
      av_write_trailer(ofmt_ctx);
  
  end:
  
      av_packet_unref(&amp;packet);
  
      av_frame_free(&amp;frame);
  
      for (i = 0; i &lt; ifmt_ctx->nb_streams; i++) {
  
          // Just video
  
          if (i != videoStreamIndex)
  
              continue;
  
          avcodec_free_context(&amp;stream_ctx[i].dec_ctx);
  
          if (ofmt_ctx &amp;&amp; ofmt_ctx->nb_streams > i &amp;&amp; ofmt_ctx->streams[i] &amp;&amp; stream_ctx[i].enc_ctx)
  
              avcodec_free_context(&amp;stream_ctx[i].enc_ctx);
  
          if (filter_ctx &amp;&amp; filter_ctx[i].filter_graph)
  
              avfilter_graph_free(&amp;filter_ctx[i].filter_graph);
  
      }
  
      av_free(filter_ctx);
  
      av_free(stream_ctx);
  
      avformat_close_input(&amp;ifmt_ctx);
  
      if (ofmt_ctx &amp;&amp; !(ofmt_ctx->oformat->flags &amp; AVFMT_NOFILE))
  
          avio_closep(&amp;ofmt_ctx->pb);
  
      avformat_free_context(ofmt_ctx);
  
  
  
      /*if (ret &lt; 0)
  
          av_log(NULL, AV_LOG_ERROR, "Error occurred: %s\n", av_err2str(ret));*/
  
  
  
      return ret ? 1 : 0;
  
  }
  
  </output></vector>

• Streaming MP4 frames to HTML5, what am I doing wrong ?

  5 septembre 2014, par mczarnek

  Currently I am generating a MP4 Bitstream using Intel’s Media SDK library, which uses ffmpeg underneath the covers. I can generate a mp4 file, and play it and it works.

  However, when I try to stream that mp4 across the network, it doesn’t play within the HTML5 video player, as tested within Chrome, Firefox, or IE.

  This much is sent back and forth across the network :

  Sent by Chrome:
  
  GET / HTTP/1.1
  
  Host: localhost:8085
  
  Connection: keep-alive
  
  User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.102 Safari/537.36
  
  Accept-Encoding: identity;q=1, *;q=0
  
  Accept: */*
  
  Accept-Language: en-US,en;q=0.8
  
  Range: bytes=0-
  
  
  
  From my video player:
  
  HTTP/1.1 200 OK
  
  Server: Microsoft-HTTPAPI/2.0
  
  Date: Thu, 09 Jan 2014 17:28:14 GMT
  
  Content-type: video/mp4

  After this, I send a newline, and all the video frames, one after another, while listening to see if I receive anything back from the browser.

  Then nothing happens. Any suggestions to get this playing video ? Thank you !

• Recording screencast using ffmpeg produces audio that is out of sync with the video

  7 décembre 2014, par AgilE

  I’m on Fedora 20. I got it pre-compiled from the repo.

  I use the follow command to record screencasts :

  ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1366x768 -i :0.0 -acodec pcm_s16le -vcodec libx264 -preset ultrafast -crf 0 -threads 0 filename.mkv

  The audio is perfectly synced with the video at the beginning. However, as the video progresses, the audio starts lagging behind severely (say a lag of more than 4 seconds). I’ve included a sample output that ffmpeg shows while recording a video.

  ffmpeg version 2.1.3 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jan 25 2014 15:11:42 with gcc 4.8.2 (GCC) 20131212 (Red Hat 4.8.2-7)
  
    configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-libass --enable-libcdio --enable-libcelt --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
  
    libavutil      52. 48.101 / 52. 48.101
  
    libavcodec     55. 39.101 / 55. 39.101
  
    libavformat    55. 19.104 / 55. 19.104
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 90.100 /  3. 90.100
  
    libavresample   1.  1.  0 /  1.  1.  0
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, alsa, from 'pulse':
  
    Duration: N/A, start: 1391533629.323015, bitrate: 1536 kb/s
  
      Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  [x11grab @ 0x153ad80] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1366 height: 768
  
  [x11grab @ 0x153ad80] shared memory extension found
  
  Input #1, x11grab, from ':0.0':
  
    Duration: N/A, start: 1391533629.365274, bitrate: 1007124 kb/s
  
      Stream #1:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1366x768, 1007124 kb/s, 30 tbr, 1000k tbn, 30 tbc
  
  [swscaler @ 0x1520460] deprecated pixel format used, make sure you did set range correctly
  
  No pixel format specified, yuv444p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x1551420] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x1551420] profile High 4:4:4 Predictive, level 3.2, 4:4:4 8-bit
  
  [libx264 @ 0x1551420] 264 - core 138 r2363 c628e3b - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
  
  Output #0, matroska, to 'testing.mkv':
  
    Metadata:
  
      encoder         : Lavf55.19.104
  
      Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 1366x768, q=-1--1, 1k tbn, 30 tbc
  
      Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (rawvideo -> libx264)
  
    Stream #0:0 -> #0:1 (pcm_s16le -> pcm_s16le)
  
  Press [q] to stop, [?] for help
  
  [swscaler @ 0x1520460] Warning: data is not aligned! This can lead to a speedloss
  
  frame=  213 fps= 27 q=-1.0 Lsize=    3572kB time=00:00:08.00 bitrate=3653.6kbits/s    
  
  video:2025kB audio:1501kB subtitle:0 global headers:0kB muxing overhead 1.291094%
  
  [libx264 @ 0x1551420] frame I:1     Avg QP: 0.00  size:692585
  
  [libx264 @ 0x1551420] frame P:212   Avg QP: 0.00  size:  6509
  
  [libx264 @ 0x1551420] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x1551420] mb P  I16..4: 47.2%  0.0%  0.0%  P16..4:  0.1%  0.0%  0.0%  0.0%  0.0%    skip:52.8%
  
  [libx264 @ 0x1551420] coded y,u,v intra: 0.7% 0.7% 0.7% inter: 0.1% 0.1% 0.1%
  
  [libx264 @ 0x1551420] i16 v,h,dc,p: 100%  0%  0%  0%
  
  [libx264 @ 0x1551420] kb/s:2335.32

  Is there something I’m missing ?