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• ffmpeg convert .mpg to .m2v

  15 août 2016, par John Doe 2

  I try to convert a .mpg file into a .m2v file.

  I am using this line :

  ffmpeg -i video.mpg -s 720x576 -c:a copy videoNew.m2v

  The .mpg file has a video length of 00:49:99 when I rightclick on the file and go to the properties, but the .m2v has a strange video length of 256204778:48:05.

  Why does this happen and how do I solve this ?

• ffmpeg:transcoding.c problems

  25 novembre 2016, par Park Han Wool

  I am studying about ffmpeg in c++ to see example of ffmpeg

  but I dont’ know how to solve this problem in transcoding.c

  here is my problem

  

  and here is code

  static int open_output_file(const char *filename)
  
  {
  
  
  
      AVCodecContext *dec_ctx, *enc_ctx;
  
      AVCodec *encoder;
  
      AVStream *in_stream, *out_stream;
  
      int ret;
  
      unsigned int i;
  
      ofmt_ctx = NULL;
  
  
  
      avformat_alloc_output_context2(&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 < ifmt_ctx->nb_streams; i++) {
  
  
  
          in_stream = ifmt_ctx->streams[i];
  
          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;
  
          }
  
  
  
  
  
              dec_ctx = in_stream->codec;
  
              enc_ctx = out_stream->codec;
  
  
  
  
  
          printf("codec name : %s \n", avcodec_get_name(enc_ctx->codec_id));
  
  
  
  
  
  
  
          if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO || dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
              /* 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;
  
              }
  
  
  
              /* In this example, we transcode to same properties (picture size,
  
              * sample rate etc.). These properties can be changed for output
  
              * streams easily using filters */
  
              if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
  
  
  
                  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 */
  
                  enc_ctx->pix_fmt = encoder->pix_fmts[0];
  
  
  
                  /* video time_base can be set to whatever is handy and supported by encoder */
  
                  enc_ctx->time_base = dec_ctx->time_base;
  
              }
  
  
  
              else {
  
                  enc_ctx->sample_rate = dec_ctx->sample_rate;
  
                  enc_ctx->channel_layout = dec_ctx->channel_layout;
  
                  enc_ctx->channels = av_get_channel_layout_nb_channels(enc_ctx->channel_layout);
  
  
  
                  /* take first format from list of supported formats */
  
                  enc_ctx->sample_fmt = encoder->sample_fmts[0];
  
                  enc_ctx->time_base.num = 1;
  
                  enc_ctx->time_base.den = enc_ctx->sample_rate;
  
              }
  
  
  
  
  
  
  
              /* Third parameter can be used to pass settings to encoder */
  
              ret = avcodec_open2(enc_ctx, encoder, NULL);
  
  
  
              if (ret < 0) {
  
                  cout << "ret<0" << endl;
  
                  av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
          }
  
          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_copy_context(ofmt_ctx->streams[i]->codec,
  
                  ifmt_ctx->streams[i]->codec);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Copying stream context failed\n");
  
                  return ret;
  
              }
  
          }
  
  
  
          if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
  
              enc_ctx->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
      }
  
  
  
      av_dump_format(ofmt_ctx, 0, filename, 1);
  
  
  
      if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {
  
          ret = avio_open(&ofmt_ctx->pb, filename, AVIO_FLAG_WRITE);
  
          if (ret < 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 < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Error occurred when opening output file\n");
  
          return ret;
  
      }
  
      return 0;
  
  
  
  }

  I found this problem in open_output_file function....

  but I can’t fix this problem..

  how I can approach this problem..

  I need your help,.

• Seek a .mp4 video using FFmpeg and out put as .mov in iOS

  14 juillet 2015, par AnujAroshA

  In my iOS project, I am using .mp4 video file which located inside my project to seek to a particular location and convert the output as .mov file. I want to achieve this using FFmpeg without any wrapper.

  I was able to build FFmpeg libraries for iOS using this script and then I added them to my project as well.

  This is the fully code that I have used to achieve my seek and convert target.

  The issues with final output of the file are :

  1. Video Duration and Dimensions properties are empty even it plays for 2 minutes and 7 seconds (Actual video has 5 minutes and 47 seconds)
  2. Video is fast-forwarding for 6 seconds and halt there till the clip ends
  3. In the code I gave seek time to 100 seconds but both audio and video streams starts from the beginning just like the actual video file