Recherche avancée

Sur d’autres sites (2950)

• ffmpeg sync issue when muxing audio and video

  25 août 2018, par tweecore

  I have an issue with ffmpeg. I am not a pro user so I’m on a constant trial & error mode. I would need a little help from this community that helped me countless time before.
  I downloaded separate audio and video segments of a video stream. Both audio and video were shown in the Network tab as being .m4s files, but the .m3u8 playlist gave me .ts files for both. So then I downloaded the whole audio batch and concatenated it into a single .ts file. I did the same with video, but using a .mp4 output.
  

  EDIT : When merging the audio .ts files, I encounter this issue :

  [mpegts @ 0x7f88cb805600] Non-monotonous DTS in output stream 0:0; 
  
  previous: 1077120, current: 1073280; changing to 1077121. This may 
  
  result in incorrect timestamps in the output file.

  UPDATE : Just noticed that when I examine the .ts audio file with MediaInfo, the frame rate is 41.667 fps (1152 SPF).

  So now I have two files : a working single .ts with audio and a working single .mp4 with video.
  Only when I tried to merge them, however, I noticed that audio and video resulted as out of sync.
  This is because audio has a different length from video (don’t know why, they were the same amount of segments : 750).
  Audio info :

  Input #0, mpegts, from 'output.ts':
  
  Duration: 01:14:12.11, start: 1.400000, bitrate: 434 kb/s
  
  Program 1 
  
  Metadata:
  
    service_name    : Service01
  
    service_provider: FFmpeg
  
  Stream #0:0[0x100]: Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 384 kb/s

  I can see that for some reason, it starts at 1.4s.

  Video info :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.mp4':
  
  Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  encoder         : Lavf58.12.100
  
  Duration: 01:14:57.84, start: 0.000000, bitrate: 2425 kb/s
  
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720 [SAR 1:1 DAR 16:9], 2423 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc (default)
  
  Metadata:
  
    handler_name    : VideoHandler

  Video and audio are synced at the beginning (somehow the 1.4 start makes sense) but audio starts drifting and goes out of sync after a while. How do I solve the issue ?

• ffmpeg : mix/merge multiple mp3 files, some do not mix

  28 août 2018, par C. Ovidiu

  I am trying to merge multiple mp3 files on top of each other on a CentOS 7 server.

  I am trying with ffmpeg but I have mixed results. When mixing 4 files, the last one for example does not mix with the others and is not audible in the final output.

  If I mix this file with another one or two(so max 3 files merged), it works.

  Is there a limit when merging ? For reference, each file is about 10mb is size and 5:00 minutes long.

  This is the command I am using

  ffmpeg -i /var/www/vhosts/site/httpdocs/uploads/tracks/1.mp3 -i /var/www/vhosts/site/httpdocs/uploads/tracks/2.mp3 -i /var/www/vhosts/site/httpdocs/uploads/tracks/3.mp3 -i /var/www/vhosts/site/httpdocs/uploads/tracks/4.mp3 -filter_complex amerge -ac 2 -c:a libmp3lame -q:a 4 /var/www/vhosts/site/httpdocs/uploads/mix.mp3

  The output after merging is this :

  ffmpeg version 2.8.15 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-28)
  
    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' --extra-ldflags='-Wl,-z,relro ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libx265 --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      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [mp3 @ 0x1c8ba60] Skipping 0 bytes of junk at 1044.
  
  Input #0, mp3, from '/var/www/vhosts/site/httpdocs/uploads/tracks/1.mp3':
  
    Duration: 00:05:44.08, start: 0.025057, bitrate: 320 kb/s
  
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 320 kb/s
  
      Metadata:
  
        encoder         : LAME3.98r
  
      Side data:
  
        replaygain: track gain - 6.000000, track peak - unknown, album gain - unknown, album peak - unknown,
  
  [mp3 @ 0x1c8eac0] Skipping 0 bytes of junk at 2446.
  
  [mp3 @ 0x1c8eac0] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, mp3, from '/var/www/vhosts/site/httpdocs/uploads/tracks/2.mp3':
  
    Metadata:
  
      genre           : Other
  
    Duration: 00:05:44.19, start: 0.000000, bitrate: 320 kb/s
  
      Stream #1:0: Audio: mp3, 44100 Hz, stereo, s16p, 320 kb/s
  
  [mp3 @ 0x1c9d640] Skipping 0 bytes of junk at 1044.
  
  Input #2, mp3, from '/var/www/vhosts/site/httpdocs/uploads/tracks/3.mp3':
  
    Duration: 00:05:44.08, start: 0.025057, bitrate: 320 kb/s
  
      Stream #2:0: Audio: mp3, 44100 Hz, stereo, s16p, 320 kb/s
  
      Metadata:
  
        encoder         : LAME3.98r
  
      Side data:
  
        replaygain: track gain - 3.400000, track peak - unknown, album gain - unknown, album peak - unknown,
  
  [mp3 @ 0x1cc2b80] Skipping 0 bytes of junk at 1044.
  
  Input #3, mp3, from '/var/www/vhosts/site/httpdocs/uploads/tracks/4.mp3':
  
    Duration: 00:05:44.08, start: 0.025057, bitrate: 320 kb/s
  
      Stream #3:0: Audio: mp3, 44100 Hz, stereo, s16p, 320 kb/s
  
      Metadata:
  
        encoder         : LAME3.98r
  
      Side data:
  
        replaygain: track gain - 12.100000, track peak - unknown, album gain - unknown, album peak - unknown,
  
  [Parsed_amerge_0 @ 0x1cc34e0] No channel layout for input 1
  
  [Parsed_amerge_0 @ 0x1cc34e0] Input channel layouts overlap: output layout will be determined by the number of distinct input channels
  
  Output #0, mp3, to '/var/www/vhosts/site/httpdocs/uploads/mix.mp3':
  
    Metadata:
  
      TSSE            : Lavf56.40.101
  
      Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, stereo, s16p (default)
  
      Metadata:
  
        encoder         : Lavc56.60.100 libmp3lame
  
  Stream mapping:
  
    Stream #0:0 (mp3) -> amerge:in0
  
    Stream #1:0 (mp3) -> amerge:in1
  
    amerge -> Stream #0:0 (libmp3lame)
  
  Press [q] to stop, [?] for help
  
  size=    2360kB time=00:05:44.03 bitrate=  56.2kbits/s
  
  video:0kB audio:2360kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.010468%

  Is there a way to solve this, or at least to know what the issue is ?

  Also, some people recommended sox, but I can’t figure how to install it on CentOS.

  Any other alternatives will also help.

  Thank you

• libav how to change stream codec

  9 novembre 2018, par Rodolfo Picoreti

  I am trying to reproduce with libav the same thing that the following ffmpeg command does :

  ffmpeg -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video 0 -f
  mpegts -codec:v mpeg1video -s 640x480 -b:v 1000k -bf 0 -muxdelay
  0.001 http://localhost:8081/supersecret

  I manage to reproduce most part of it. The problem is that when allocating the "mpegts" stream (line 23) the codec that is selected is "mpeg2video", but I need it to be "mpeg1video". I tried forcing the codec_id variable to be "mpeg1video" (line 25) and it kinda worked, although I get a lot of artifacts in the image so I am guessing this is not how you do it. How can I properly change the codec in this case (that is, the "-codec:v mpeg1video" part of the ffmpeg command) ?

  C++ code being used :

  #include <exception>
  
  #include <opencv2></opencv2>core.hpp>
  
  #include <opencv2></opencv2>highgui.hpp>
  
  #include <opencv2></opencv2>imgproc.hpp>
  
  
  
  extern "C" {
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavutil></libavutil>error.h>
  
  #include <libavutil></libavutil>frame.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  }
  
  
  
  struct AVStreamer {
  
    AVFormatContext* format_context;
  
    AVStream* stream;
  
    AVCodecContext* codec_context;
  
    AVCodec* codec;
  
    AVFrame* frame;
  
    int64_t next_pts;
  
  
  
    void init_format_context(const char* url) {
  
      avformat_alloc_output_context2(&amp;format_context, nullptr, "mpegts", url);
  
      if (format_context == nullptr) throw std::runtime_error("Could not create output context");
  
      format_context->oformat->video_codec = AV_CODEC_ID_MPEG1VIDEO;
  
    }
  
  
  
    void init_codec() {
  
      auto codec_id = format_context->oformat->video_codec;
  
      codec = avcodec_find_encoder(codec_id);
  
      if (codec == nullptr) throw std::runtime_error("Could not find encoder");
  
    }
  
  
  
    void init_stream() {
  
      stream = avformat_new_stream(format_context, nullptr);
  
      if (stream == nullptr) throw std::runtime_error("Failed to alloc stream");
  
      stream->id = format_context->nb_streams - 1;
  
    }
  
  
  
    void init_codec_context() {
  
      codec_context = avcodec_alloc_context3(codec);
  
      if (codec_context == nullptr) throw std::runtime_error("Failed to alloc encoding context");
  
  
  
      auto codec_id = format_context->oformat->video_codec;
  
      codec_context->codec_id = codec_id;
  
      codec_context->bit_rate = 400000;
  
      codec_context->width = 640;
  
      codec_context->height = 480;
  
      stream->time_base = AVRational{1, 30};
  
      codec_context->time_base = stream->time_base;
  
      codec_context->gop_size = 30;  // one intra frame every gop_size
  
      // codec_context->max_b_frames = 0;  // output delayed by max_b_frames
  
      codec_context->pix_fmt = AV_PIX_FMT_YUV420P;
  
      if (codec_context->codec_id == AV_CODEC_ID_MPEG1VIDEO) { codec_context->mb_decision = 2; }
  
      if (format_context->oformat->flags &amp; AVFMT_GLOBALHEADER) {
  
        codec_context->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
      }
  
    }
  
  
  
    void init_frame() {
  
      frame = av_frame_alloc();
  
      if (frame == nullptr) throw std::runtime_error("Failed to alloc frame");
  
      frame->format = codec_context->pix_fmt;
  
      frame->width = codec_context->width;
  
      frame->height = codec_context->height;
  
  
  
      auto status = av_frame_get_buffer(frame, 32);
  
      if (status &lt; 0) { throw std::runtime_error("Could not allocate frame data.\n"); }
  
    }
  
  
  
    void open_stream(const char* url) {
  
      int status = avcodec_open2(codec_context, codec, nullptr);
  
      if (status != 0) throw std::runtime_error("Failed to open codec");
  
  
  
      // copy the stream parameters to the muxer
  
      status = avcodec_parameters_from_context(stream->codecpar, codec_context);
  
      if (status &lt; 0) throw std::runtime_error("Could not copy the stream parameters");
  
  
  
      av_dump_format(format_context, 0, url, 1);
  
  
  
      if (!(format_context->oformat->flags &amp; AVFMT_NOFILE)) {
  
        status = avio_open(&amp;format_context->pb, url, AVIO_FLAG_WRITE);
  
        if (status &lt; 0) throw std::runtime_error("Could not open output file");
  
      }
  
  
  
      // Write the stream header, if any.
  
      status = avformat_write_header(format_context, nullptr);
  
      if (status &lt; 0) throw std::runtime_error("Error occurred when opening output file");
  
    }
  
  
  
    AVStreamer(const char* url) : next_pts(0) {
  
      init_format_context(url);
  
      init_codec();
  
      init_stream();
  
      init_codec_context();
  
      init_frame();
  
      open_stream(url);
  
    }
  
  
  
    virtual ~AVStreamer() {
  
      avformat_free_context(format_context);
  
      avcodec_free_context(&amp;codec_context);
  
      av_frame_free(&amp;frame);
  
    }
  
  
  
    void send(cv::Mat const&amp; image) {
  
      cv::cvtColor(image, image, CV_BGR2YUV);
  
      cv::Mat planes[3];
  
      cv::split(image, planes);
  
      cv::pyrDown(planes[1], planes[1]);
  
      cv::pyrDown(planes[2], planes[2]);
  
  
  
      if (av_frame_make_writable(frame) &lt; 0) {
  
        throw std::runtime_error("Failed to make frame writable");
  
      }
  
  
  
      frame->data[0] = planes[0].data;
  
      frame->linesize[0] = planes[0].step;
  
      frame->data[1] = planes[1].data;
  
      frame->linesize[1] = planes[1].step;
  
      frame->data[2] = planes[2].data;
  
      frame->linesize[2] = planes[2].step;
  
      frame->pts = next_pts++;
  
  
  
      AVPacket packet;
  
      av_init_packet(&amp;packet);
  
  
  
      int status = avcodec_send_frame(codec_context, frame);
  
      if (status &lt; 0) throw std::runtime_error("Send frame failed");
  
  
  
      status = avcodec_receive_packet(codec_context, &amp;packet);
  
      if (status == AVERROR(EAGAIN)) { return; }
  
      if (status &lt; 0) throw std::runtime_error("Receive packet failed");
  
  
  
      av_packet_rescale_ts(&amp;packet, codec_context->time_base, stream->time_base);
  
      packet.stream_index = stream->index;
  
      av_interleaved_write_frame(format_context, &amp;packet);
  
    }
  
  };
  
  
  
  int main(int argc, char** argv) {
  
    av_register_all();
  
    avformat_network_init();
  
  
  
    auto url = argc == 2 ? argv[1] : "http://localhost:8081/supersecret";
  
    AVStreamer streamer(url);
  
  
  
    cv::VideoCapture video(0);
  
    assert(video.isOpened() &amp;&amp; "Failed to open video");
  
  
  
    for (;;) {
  
      cv::Mat image;
  
      video >> image;
  
      streamer.send(image);
  
    }
  
  }
  
  </exception>