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• Using FFMPEG to make HLS clips from H264

  21 novembre 2017, par Tyler Brooks

  I am using a Hi35xx camera processor from HiSilicon. It is an Arm9 with a video pipeline bolted on the side. At one end of the pipeline is the CMOS sensor. At the other end is a H264 encoder. When I turn on the pipeline, the encoder outputs H264 NAL packets like this :

  frame0: <sps>,<pps>,<sei>,<key frame="frame">
  
  frame1: <delta frame="frame">
  
  frame2: <delta frame="frame">
  
  ...
  
  frameN: <delta frame="frame">
  
  frameN+1: <sps>,<pps>,<sei><key frame="frame">
  
  frameN+2: <delta frame="frame">
  
  frameN+3: <delta frame="frame">
  
  ...
  
  etc.
  
  </delta></delta></key></sei></pps></sps></delta></delta></delta></key></sei></pps></sps>

  I am turning that into HLS clips by doing the following (pseudo code for clarity) :

  av_register_all();
  
  avformat_network_init();
  
  
  
  avformat_alloc_output_context2(&ctx_out, NULL, "hls", "./foo.m3u8");
  
  
  
  strm_out = avformat_new_stream(ctx_out, NULL);
  
  
  
  codec_out = strm_out->codecpar;
  
  codec_out->codec_id = AV_CODEC_ID_H264;
  
  codec_out->codec_type = AVMEDIA_TYPE_VIDEO;
  
  codec_out->width = encoder_width;
  
  codec_out->height = encoder_height;
  
  codec_out->bit_rate = encoder_bitrate;
  
  codec_out->codec_tag = 0;
  
  
  
  avformat_write_header(ctx_out, NULL);
  
  
  
  while(get_packet_from_pipeline_encoder(&encoder_packet)) {
  
    AVPacket pkt;
  
    av_init_packet(&pkt);
  
    pkt.stream_index = 0;
  
  
  
    pkt.dts = AV_NOPTS_VALUE;
  
    pkt.pts = AV_NOPTS_VALUE;
  
    pkt.duration = (1000000/FRAMERATE);    // frame rate in microseconds
  
  
  
    pkt.data = encoder_packet.data;
  
    pkt.size = encoder_packet.size;
  
  
  
    if (is_keyframe(&encoder_packet)) {
  
      pkt.flags |= AV_PKT_FLAG_KEY;
  
    }
  
  
  
    av_write_frame(ctx_out, &pkt);
  
  }
  
  
  
  av_write_trailer(ctx_out);
  
  avformat_free_context(ctx_out);

  This seems to work fine except that the resulting HLS frame rate is not right. Of course, this happens because I am not setting the pts/dts stuff correctly and ffmpeg lets me know that. So I have two quetions :

  1. Am I going about this right ?
  2. How can I set the pts/dts stuff correctly ?

  The encoder is giving me packets and I am submitting them as frames. Those <sps>, <pps> and <sei></sei></pps></sps> packets are really out of band data and don’t really have a timestamp. How can I submit them correctly ?

• avcodec/amfdec,rkmppdec : Use correct extradata with BSFs

  11 juin, par Andreas Rheinhardt

  avcodec/amfdec,rkmppdec : Use correct extradata with BSFs
  Otherwise the extradata used would be ISOBMFF if the input is
  
  even though we use the *_mp4toannexb BSFs to convert it to
  
  annex B to feed it to the actual decoder.
  (The mediacodec decoders also use said BSFs, yet they process
  
  the extradata in a way that works even when using the ISOBMFF
  
  extradata ; in fact, using the converted extradata would break
  
  their check for whether to warn for missing extradata for
  
  the ISOBMFF without-in-band-header profiles.
  Furthermore, there are several users of the *_mp4toannexb BSFs
  
  that don't ever touch extradata. They have not been touched.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/amfdec.c
  • [DH] libavcodec/decode_bsf.h
  • [DH] libavcodec/rkmppdec.c

• can someone explain this difference between H.264 and H.265 ?

  19 janvier 2017, par Muhammad Abu bakr

  I have studied this in a research paper :

  "The off-the-shelf video codecs like H.264 handle all the movements equally. In our case there are some non moving region that lies in region of interest and need to be encode in high quality and there are some moving regions which don’t need such requirements. H.265 can help us in such circumstances."

  How H.265 deals with movements differently ?