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• avformat/mpegts : skip non-PMT tids earlier

  9 mai 2018, par Aman Gupta

  avformat/mpegts : skip non-PMT tids earlier
  This mimics the logic flow in all the other callbacks
  
  (pat_cb, sdt_cb, m4sl_cb), and avoids calling skip_identical()
  
  for non PMT_TID packets.
  Since skip_identical modifies internal state like
  
  MpegTSSectionFilter.last_ver, this change prevents unnecessary
  
  reprocessing on some streams which contain multiple tables in
  
  the PMT pid. This can be observed with streams from certain US
  
  cable providers, which include both tid=0x2 and another unspecified
  
  tid=0xc0.
  Signed-off-by : Aman Gupta <aman@tmm1.net>
  

  • [DH] libavformat/mpegts.c

• Parse closed captions from H264 stream (HDHomeRun)

  5 mai 2018, par Ladinn

  I’ve been researching on here and other websites for the past few days and haven’t found anything that accomplishes exactly what I’m looking for.

  I have an HDHomeRun that transmits cable TV over LAN. I’m hoping to parse only the closed captioning and get the text output. I’ll eventually be using Fluent FFmpeg so I would hope that the text can be easily piped through there or to a text file.

  Here is the output of ffprobe :

  Input #0, mpegts, from 'http://10.0.0.10:5004/auto/v819':
 Duration: N/A, start: 32788.639133, bitrate: N/A
 Program 6
   Stream #0:0[0x18f0]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
   Stream #0:1[0x18f1](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 384 kb/s
   Stream #0:2[0x18f2]: Data: scte_35
   Stream #0:3[0x18f3]: Unknown: none (ETV1 / 0x31565445)
   Stream #0:4[0x18f4]: Unknown: none (ETV1 / 0x31565445)
   Stream #0:5[0x18f5]: Unknown: none ([192][0][0][0] / 0x00C0)

  As you can see, "Closed Captions" are on Stream #0:0. The captions appear on the VLC client, so I know they’re there.

  As mentioned I’m hoping to use FFmpeg, but VLC’s command line would work too.

  Thanks !

• FFMPEG corrupted frame when streaming in UDP (MPEGTS)

  17 décembre 2020, par user37616

  I am working on a screen streaming program, till now, I can capture and encode my screen into a video perfectly. 
However, whenever I try to stream it over LAN, and play using Mplayer, it is able to run in simple desktop (text document, etc...) but when I try to play video the frame stated to corrupted until I quit the video (this video cause the most corrupted frame https://www.youtube.com/watch?v=1La4QzGeaaQ&t=230s)

  



  I am not really sure why when streaming, I got corrupted frame with the youtube video but when save it to a file (change URL from udp ://192.168.1.xxx:YYYY to file name C :\Test.ts) there were no corrupted frame at all.
 My Mplayer log :

  



  `V:   0.0 1563/1563 51% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 23 51, bytestream -64
[h264 @ 0000000001d04940]concealing 2066 DC, 2066 AC, 2066 MV errors in I frame
V:   0.0 1564/1564 51% 43%  0.0% 0 0
[h264 @ 0000000001d04940]concealing 7598 DC, 7598 AC, 7598 MV errors in P frame
V:   0.0 1652/1652 50% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 26 49, bytestream -55
[h264 @ 0000000001d04940]concealing 2303 DC, 2303 AC, 2303 MV errors in I frame
V:   0.0 1653/1653 50% 43%  0.0% 0 0
[h264 @ 0000000001d04940]concealing 7727 DC, 7727 AC, 7727 MV errors in P frame
V:   0.0 1741/1741 49% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 65 62, bytestream -57
[h264 @ 0000000001d04940]concealing 704 DC, 704 AC, 704 MV errors in I frame
V:   0.0 1742/1742 49% 43%  0.0% 0 0`


  



  Stream initialize code

  



  static void Stream_ini(const char *Url, AVFormatContext *&ofmt_ctx, AVCodec *codec, AVCodecContext *c, AVStream *&out_stream)
{
    int ret;


    avformat_alloc_output_context2(&ofmt_ctx, NULL, "mpegts", Url);
    out_stream = avformat_new_stream(ofmt_ctx, codec)
    out_stream->codec = c;
    av_dump_format(ofmt_ctx, 0, Url, 1);


    if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
        out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    if (!(ofmt_ctx->flags & AVFMT_NOFILE))
    {
        ret = avio_open(&ofmt_ctx->pb, Url, AVIO_FLAG_WRITE);
        if (ret < 0)
        {
            printf("Could not open output URL '%s'", Url);
            return;
        }
    }


    ret = avformat_write_header(ofmt_ctx, NULL);

    if (ret < 0)
    {
        printf("Error occurred when opening output URL\n");
        return;
    }


}


  



  this code will get the captured screen and send it to encoder :

  



  ScreenCap.load_screen_data(inFrame,timmer)  // this will capture screen and return the time and AVFrame for encoding
sws_scale(ctx, inFrame->data, inFrame->linesize, 0,c->height, frame->data, frame->linesize);

frame->pts = (timmer - first_frame_time) / fps;
EncodeToPkT(c, frame, pkt, ofmt_ctx,out_stream);

av_frame_free(&inFrame);


  



  the AVFrame will then be send to encoder using avcodec_send_frame() to get Packet data and av_interleaved_write_frame() to stream it over LAN.

  



  All error check are removed for simplicity

  



  Also, this is my AVCodecContex setting for the encoder :

  



  c->bit_rate = 15000000;
c->width = 1920;
c->height = 1080;
c->time_base = AVRational{ 1, 90 };
c->framerate = AVRational{ 90, 1 };
c->gop_size = 90;
c->max_b_frames = 0;
c->pix_fmt = AV_PIX_FMT_RGB0;


  



  I also notice it only happen when I increase encoder bitrate (15 MBIT) but when lower it down to (10 MBIT) it happen less. And when lower it down to 2 MBIT the corrupted frame not happen anymore however the quality is really bad.
  
I test the streaming in LAN using : PC -> cable ->laptop, PC->wireless->laptop, PC->Virtual PC, PC only (enter PC IP address in both program and Mplayer), all got the same result.

  



  I also test my DXGICap.load_screen_data function by make it output raw image and there were no corrupted image at all

  



  Does anybody have an idea why.

  



  Thank Nam.