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• FFMPEG RTSP stream to MPEG4/H264 file using libx264

  16 octobre 2020, par Phi

  Heyo folks,

  



  I'm attempting to transcode/remux an RTSP stream in H264 format into a MPEG4 container, containing just the H264 video stream. Basically, webcam output into a MP4 container.

  



  I can get a poorly coded MP4 produced, using this code :

  



  // Variables here for demo
AVFormatContext * video_file_output_format = nullptr;
AVFormatContext * rtsp_format_context = nullptr;
AVCodecContext * video_file_codec_context = nullptr;
AVCodecContext * rtsp_vidstream_codec_context = nullptr;
AVPacket packet = {0};
AVStream * video_file_stream = nullptr;
AVCodec * rtsp_decoder_codec = nullptr;
int errorNum = 0, video_stream_index = 0;
std::string outputMP4file = "D:\\somemp4file.mp4";

// begin
AVDictionary * opts = nullptr;
av_dict_set(&opts, "rtsp_transport", "tcp", 0);

if ((errorNum = avformat_open_input(&rtsp_format_context, uriANSI.c_str(), NULL, &opts)) < 0) {
    errOut << "Connection failed: avformat_open_input failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

rtsp_format_context->max_analyze_duration = 50000;
if ((errorNum = avformat_find_stream_info(rtsp_format_context, NULL)) < 0) {
    errOut << "Connection failed: avformat_find_stream_info failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

video_stream_index = errorNum = av_find_best_stream(rtsp_format_context, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);

if (video_stream_index < 0) {
    errOut << "Connection in unexpected state; made a connection, but there was no video stream.\r\n"
        "Attempts to find a video stream resulted in error " << errorNum << ": " << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

rtsp_vidstream_codec_context = rtsp_format_context->streams[video_stream_index]->codec;

av_init_packet(&packet);

if (!(video_file_output_format = av_guess_format(NULL, outputMP4file.c_str(),  NULL))) {
    TacticalAbort();
    throw std::exception("av_guess_format");
}

if (!(rtsp_decoder_codec = avcodec_find_decoder(rtsp_vidstream_codec_context->codec_id))) {
    errOut << "Connection failed: connected, but avcodec_find_decoder returned null.\r\n"
        "Couldn't find codec with an AV_CODEC_ID value of " << rtsp_vidstream_codec_context->codec_id << ".";
    TacticalAbort();
    return;
}

video_file_format_context = avformat_alloc_context();
video_file_format_context->oformat = video_file_output_format;

if (strcpy_s(video_file_format_context->filename, sizeof(video_file_format_context->filename), outputMP4file.c_str())) {
    errOut << "Couldn't open video file: strcpy_s failed with error " << errno << ".";
    std::string log = errOut.str();
    TacticalAbort();
    throw std::exception("strcpy_s");
}

if (!(video_file_encoder_codec = avcodec_find_encoder(video_file_output_format->video_codec))) {
    TacticalAbort();
    throw std::exception("avcodec_find_encoder");
}

// MARKER ONE

if (!outputMP4file.empty() &&
    !(video_file_output_format->flags & AVFMT_NOFILE) &&
    (errorNum = avio_open2(&video_file_format_context->pb, outputMP4file.c_str(), AVIO_FLAG_WRITE, nullptr, &opts)) < 0) {
    errOut << "Couldn't open video file \"" << outputMP4file << "\" for writing : avio_open2 failed with error " << errorNum << ": " << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

// Create stream in MP4 file
if (!(video_file_stream = avformat_new_stream(video_file_format_context, video_file_encoder_codec))) {
    TacticalAbort();
    return;
}

AVCodecContext * video_file_codec_context = video_file_stream->codec;

// MARKER TWO

// error -22/-21 in avio_open2 if this is skipped
if ((errorNum = avcodec_copy_context(video_file_codec_context, rtsp_vidstream_codec_context)) != 0) {
    TacticalAbort();
    throw std::exception("avcodec_copy_context");
}

//video_file_codec_context->codec_tag = 0;

/*
// MARKER 3 - is this not needed? Examples suggest not.
if ((errorNum = avcodec_open2(video_file_codec_context, video_file_encoder_codec, &opts)) < 0)
{
    errOut << "Couldn't open video file codec context: avcodec_open2 failed with error " << errorNum << ": " << ErrorRead(errorNum);
    std::string log = errOut.str();
    TacticalAbort();
    throw std::exception("avcodec_open2, video file");
}*/

//video_file_format_context->flags |= AVFMT_FLAG_GENPTS;
if (video_file_format_context->oformat->flags & AVFMT_GLOBALHEADER)
{
    video_file_codec_context->flags |= CODEC_FLAG_GLOBAL_HEADER;
}

if ((errorNum = avformat_write_header(video_file_format_context, &opts)) < 0) {
    errOut << "Couldn't open video file: avformat_write_header failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    std::string log = errOut.str();
    TacticalAbort();
    return;
}


  



  However, there are several issues :

  



  

  1. I can't pass any x264 options to the output file. The output H264 matches the input H264's profile/level - switching cameras to a different model switches H264 level.

  


  2. The timing of the output file is off, noticeably.

  


  3. The duration of the output file is off, massively. A few seconds of footage becomes hours, although playtime doesn't match. (FWIW, I'm using VLC to play them.)

  


  



  Passing x264 options

  



  If I manually increment PTS per packet, and set DTS equal to PTS, it plays too fast, 2-3 seconds' worth of footage in one second playtime, and duration is hours long. The footage also blurs past several seconds, about 10 seconds' footage in a second.

  



  If I let FFMPEG decide (with or without GENPTS flag), the file has a variable frame rate (probably as expected), but it plays the whole file in an instant and has a long duration too (over forty hours for a few seconds). The duration isn't "real", as the file plays in an instant.

  



  At Marker One, I try to set the profile by passing options to avio_open2. The options are simply ignored by libx264. I've tried :

  



  av_dict_set(&opts, "vprofile", "main", 0);
av_dict_set(&opts, "profile", "main", 0); // error, missing '('
// FF_PROFILE_H264_MAIN equals 77, so I also tried
av_dict_set(&opts, "vprofile", "77", 0); 
av_dict_set(&opts, "profile", "77", 0);


  



  It does seem to read the profile setting, but it doesn't use them. At Marker Two, I tried to set it after the avio_open2, before avformat_write_header .

  



  // I tried all 4 av_dict_set from earlier, passing it to avformat_write_header.
// None had any effect, they weren't consumed.
av_opt_set(video_file_codec_context, "profile", "77", 0);
av_opt_set(video_file_codec_context, "profile", "main", 0);
video_file_codec_context->profile = FF_PROFILE_H264_MAIN;
av_opt_set(video_file_codec_context->priv_data, "profile", "77", 0);
av_opt_set(video_file_codec_context->priv_data, "profile", "main", 0);


  



  Messing with privdata made the program unstable, but I was trying anything at that point.
I'd like to solve issue 1 with passing settings, since I imagine it'd bottleneck any attempt to solve issues 2 or 3.

  



  I've been fiddling with this for the better part of a month now. I've been through dozens of documentation, Q&As, examples. It doesn't help that quite a few are outdated.

  



  Any help would be appreciated.

  



  Cheers

  


• Revision 03fe08ca30 : Deprecate the use of PARTITION_INFO from encoder Use b_mode_info to store the i

  7 octobre 2013, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_bitstream.c

  
   Modify /vp9/encoder/vp9_block.h

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_encodemv.c

  
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Deprecate the use of PARTITION_INFO from encoder

  Use b_mode_info to store the inter prediction mode of sub8x8 block,
  in replacement of the use of partition_info. Remove redundant buffer
  update for partition_info. For bus_cif at 2000 kbps, this seem to make
  speed 0 about 1% faster.

  Change-Id : Id1b3be45e75a24fb4b42335ac480c23e440978f6

• How can I mux (or encapsulate) H.264 RTP output into a container using FFMPEG ?

  7 octobre 2013, par Grad

  I am working on the effects of network losses in video transmission. In order to simulate the network losses I use a simple program which drops random RTP packets from the output of H.264 RTP encoding.

  I use Joint Model (JM) 14.2 in order to encode the video. However, I don't use AnnexB format as my output, instead I choose the output as RTP packets. The JM output is generated as RTP packets with RTP headers and payload as a sequence. After that, some of RTP packets are dropped by using a simple program. Then, I can decode the output bitstream by using also JM and it's error concealment methods.

  The main purpose of this process is to evaluate the differences created by network losses on the human video quality perception. In order to measure the perceived quality, the shown video must be in its decoded form (i.e. full resolution) or it can be decodable at the receiver side. The RTP packets created by the JM Encoder cannot be decoded without the JM software installed. However, with the proper header (or container) most video players are able to decode the bitstream. So, the my goal in this question is to encapsulate my encoded RTP packet bitstream in a common container such as AVI or MP4 to have my content decodable at the receiver computer.

  The format of the encoded bitstream in RTP packetized form is as follows :

       ----------------------------------------------------------------------
  
       | RTP Header #1 | RTP Payload #1 | RTP Header #2 | RTP Payload #2 |...
  
       ----------------------------------------------------------------------

  In order to find the video quality, I want to make a subjective test with these bitstreams. I can make these test by using the full resolution data decoded by myself whereas it's very inconvenient to crowdsource this subjective test with GBs of video data on the Internet. So, I want to mux these bitstreams into a container (i.e. AVI) by using FFMPEG. I have tried to decode these bitstreams with FFMPEG and FFPLAY ; however, both of them didn't work. I also tried the following command and it didn't work, either.

      ffmpeg - f h264 -i  -vcodec copy -r 25 out.avi

  Which format or muxer should I use ? Do I need to convert these files to any other format ?