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• How can I make ffmpeg output proper SDP data for a data stream

  8 juillet 2021, par Shalom Crown

  I have a program based on the FFMPEG libraries, to add KLV data to a video stream. When I try to sent the output to an RTSP server (rtsp-simple-server), I get a 400 response.

  


  The apparent reason is that the SDP data for the KLV stream is missing the rtpmap.

  


  I would like to add the missing data either by setting the proper parameters in the contexts, or by specifying the data explicitly.

  


  This is the ANNOUNCE captured with Wireshark

  


  ANNOUNCE rtsp://0.0.0.0:8554/test RTSP/1.0
Content-Type: application/sdp
CSeq: 2
User-Agent: Lavf58.29.100
Content-Length: 270

v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 58.29.100
m=video 0 RTP/AVP 96
b=AS:10000
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1
a=control:streamid=0
m=application 0 RTP/AVP 97
b=AS:90
a=control:streamid=1


  


  Code fragment for initializing the data stream :

  


  AVStream* data_track = avformat_new_stream(muxer, nullptr);

if (data_track == nullptr) {
    LOG_ERROR << "failed to open data output stream";
    return nullptr;
}

muxer->oformat->video_codec = AV_CODEC_ID_H264;

AVCodec *klvEncoder = avcodec_find_encoder(AV_CODEC_ID_SMPTE_KLV);

if (klvEncoder == nullptr) {
    klvEncoder = avcodec_find_encoder(AV_CODEC_ID_BIN_DATA);
}

if (klvEncoder == nullptr) {
    klvEncoder = avcodec_find_encoder(AV_CODEC_ID_TEXT);
}

if (klvEncoder != nullptr) {
    klvEncoderContext = avcodec_alloc_context3(encoder);

    avcodec_parameters_from_context(data_track->codecpar, encoderContext);
} else {
    avcodec_parameters_copy(data_track->codecpar, pVideoStream->codecpar);
}

data_track->codecpar->codec_tag =  KLV_ID_TAG;
data_track->codecpar->codec_type = AVMEDIA_TYPE_DATA;
data_track->codecpar->codec_id = AV_CODEC_ID_SMPTE_KLV;
data_track->codecpar->bit_rate = 90000;
data_track->codecpar->format =  AV_SAMPLE_FMT_U8;
data_track->stream_identifier = KLV_ID_TAG;
data_track->id = 0x101;
data_track->time_base = video_track->time_base;
data_track->avg_frame_rate = video_track->time_base;


  


• libswscale/x86/hscale_fast_bilinear_simd.c : There’s no need to save BX if it’s in...

  13 mai 2015, par Nick Lewycky

  libswscale/x86/hscale_fast_bilinear_simd.c : There’s no need to save BX if it’s in the clobber list.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libswscale/x86/hscale_fast_bilinear_simd.c

• Read and Save rtsp stream using FFMPEG using python with less memory size

  25 août 2022, par Vishak Raj

  I am trying to read a rtsp stream and save in a file, for that I am using the ffmpeg in python

  


  import ffmpeg

stream = ffmpeg.input(rtsp_link, t=10)
print(stream)

file = stream.output("test.mp4")
testfile = file.run()#capture_stdout=True, capture_stderr=True


  


  but this save the video file in high space, for 10 second video, the file occupies around 3 Mb, how to reduce the file size

  


  thanks