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• Delay in displaying a video stream after streaming by libavformat

  15 janvier 2014, par Blue Sky

  I am using libavformat library to stream a video at a network address like udp ://127.0.0.1:1000. I use ffplay to display the received video stream at the network address. However, the video appears few second later (e.g. 5 6 seconds) at ffplay on the same machine. Do you know what is the reason ?

  More info :

  I have written my own streaming application using libavformat. When I stream a 3sec 1080p video at 25fps, ffplay does not show anything. If I repeat streaming the same video once again, this time, ffplay starts displaying the previous streamed video as well as the current video. So, it looks like ffplay waits for a buffer to be filled up by some amount, and then displays the stream. But am I correct ?

• Check an address to see if there is any video stream on it or not

  12 janvier 2014, par Blue Sky

  I want to read a video stream from a UDP address using libavcodec functions. To do so, I use the following code :

   char *url = "udp://127.0.0.1:1000";
  
   AVFormatContext *oc = NULL;
  
   avformat_open_input(&oc, url, NULL , NULL);

  If we run this code, then function "avformat_open_input" starts listening on the given UDP address, and it looks like the program is halted if there is no video stream at the given UDP address.

  Now, I want to write a code to first check the given UDP address quickly to see whether there is any data on it or not, if there is no data then the program should neglect running "avformat_open_input", otherwise it should run this function so that I can avoid the halting situation.

  Any idea how I can do this ? Thanks !

• Video becomes choppy when the order in the hstack filter is changed

  25 octobre 2018, par Mayank

  I have a FFmpeg command wherein I am merging 2 videos side by side using hstack filter. When I place first video on the right hand side and second video on the left hand side, the final merged video is perfect in quality and plays smoothly.

  However, when I swap the order in hstack filter, the final video is very choppy.

  Can someone please let me know the issue in this command ? Many thanks in advance.

  Also, the file size of the non working file is almost double than that of working file. Can you explain why ?

  Here is the working command :

  ffmpeg -i 1_a.opus -i 2_a.opus -itsoffset 0.024 -i 1_v.mp4 -itsoffset 0.113 -i 2_v.mp4 -filter_complex "[1:a]adelay=15646|15646[a1]; [0:a][a1]amix; [3:v]trim=0:15.646,geq=0:128:128[silence]; [3:v]fifo[3v]; [silence][3v]concat[3_v_silence]; [3_v_silence][2:v]hstack" -preset ultrafast -y n_m_bars_try2.mp4

  output :

  ffmpeg version 4.0.2-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  
    configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100
  
  Input #0, ogg, from '1_a.opus':
  
    Duration: 00:01:03.82, start: -0.020000, bitrate: 37 kb/s
  
      Stream #0:0: Audio: opus, 48000 Hz, stereo, fltp
  
  Input #1, ogg, from '2_a.opus':
  
    Duration: 00:00:52.40, start: -0.020000, bitrate: 44 kb/s
  
      Stream #1:0: Audio: opus, 48000 Hz, stereo, fltp
  
  Input #2, mov,mp4,m4a,3gp,3g2,mj2, from '1_v.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.12.100
  
    Duration: 00:01:03.85, start: 0.000000, bitrate: 2644 kb/s
  
      Stream #2:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 2633 kb/s, 333 fps, 333 tbr, 10656 tbn, 666 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Input #3, mov,mp4,m4a,3gp,3g2,mj2, from '2_v.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.12.100
  
    Duration: 00:00:52.32, start: 0.000000, bitrate: 861 kb/s
  
      Stream #3:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 860 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Stream mapping:
  
    Stream #0:0 (opus) -> amix:input0
  
    Stream #1:0 (opus) -> adelay
  
    Stream #2:0 (h264) -> hstack:input1
  
    Stream #3:0 (h264) -> trim
  
    Stream #3:0 (h264) -> fifo
  
    amix -> Stream #0:0 (aac)
  
    hstack -> Stream #0:1 (libx264)
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x528d600] using SAR=1/1
  
  [libx264 @ 0x528d600] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowShuffle
  
  [libx264 @ 0x528d600] profile Constrained Baseline, level 3.1
  
  [libx264 @ 0x528d600] 264 - core 155 r2901 7d0ff22 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
  
  Output #0, mp4, to 'navid_mayank_bars_try2.mp4':
  
    Metadata:
  
      encoder         : Lavf58.12.100
  
      Stream #0:0: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        encoder         : Lavc58.18.100 aac
  
      Stream #0:1: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1280x480 [SAR 1:1 DAR 8:3], q=-1--1, 25 fps, 12800 tbn, 25 tbc (default)
  
      Metadata:
  
        encoder         : Lavc58.18.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  frame= 1704 fps= 42 q=-1.0 Lsize=   14440kB time=00:01:08.12 bitrate=1736.5kbits/s dup=3 drop=21229 speed=1.69x    
  
  video:13448kB audio:953kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.269503%
  
  [aac @ 0x52b8680] Qavg: 22255.799
  
  [libx264 @ 0x528d600] frame I:7     Avg QP:16.29  size: 46284
  
  [libx264 @ 0x528d600] frame P:1697  Avg QP:18.36  size:  7924
  
  [libx264 @ 0x528d600] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x528d600] mb P  I16..4:  1.8%  0.0%  0.0%  P16..4: 31.0%  0.0%  0.0%  0.0%  0.0%    skip:67.2%
  
  [libx264 @ 0x528d600] coded y,uvDC,uvAC intra: 29.9% 59.3% 17.5% inter: 13.4% 24.6% 0.8%
  
  [libx264 @ 0x528d600] i16 v,h,dc,p: 36% 29% 18% 17%
  
  [libx264 @ 0x528d600] i8c dc,h,v,p: 42% 25% 21% 11%
  
  [libx264 @ 0x528d600] kb/s:1616.23

  Non working command :

  ffmpeg -i 1_a.opus -i 2_a.opus -itsoffset 0.024 -i 1_v.mp4 -itsoffset 0.113 -i 2_v.mp4 -filter_complex "[1:a]adelay=15646|15646[a1]; [0:a][a1]amix; [3:v]trim=0:15.646,geq=0:128:128[silence]; [3:v]fifo[3v]; [silence][3v]concat[3_v_silence]; [2:v][3_v_silence]hstack" -preset ultrafast -y m_n_bars_try2.mp4

  output :

  ffmpeg version 4.0.2-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  
    configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100
  
  Input #0, ogg, from '1_a.opus':
  
    Duration: 00:01:03.82, start: -0.020000, bitrate: 37 kb/s
  
      Stream #0:0: Audio: opus, 48000 Hz, stereo, fltp
  
  Input #1, ogg, from '2_a.opus':
  
    Duration: 00:00:52.40, start: -0.020000, bitrate: 44 kb/s
  
      Stream #1:0: Audio: opus, 48000 Hz, stereo, fltp
  
  Input #2, mov,mp4,m4a,3gp,3g2,mj2, from '1_v.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.12.100
  
    Duration: 00:01:03.85, start: 0.000000, bitrate: 2644 kb/s
  
      Stream #2:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 2633 kb/s, 333 fps, 333 tbr, 10656 tbn, 666 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Input #3, mov,mp4,m4a,3gp,3g2,mj2, from '2_v.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.12.100
  
    Duration: 00:00:52.32, start: 0.000000, bitrate: 861 kb/s
  
      Stream #3:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 860 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  Stream mapping:
  
    Stream #0:0 (opus) -> amix:input0
  
    Stream #1:0 (opus) -> adelay
  
    Stream #2:0 (h264) -> hstack:input0
  
    Stream #3:0 (h264) -> trim
  
    Stream #3:0 (h264) -> fifo
  
    amix -> Stream #0:0 (aac)
  
    hstack -> Stream #0:1 (libx264)
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x6d21600] using SAR=1/1
  
  [libx264 @ 0x6d21600] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowShuffle
  
  [libx264 @ 0x6d21600] profile Constrained Baseline, level 5.1
  
  [libx264 @ 0x6d21600] 264 - core 155 r2901 7d0ff22 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
  
  Output #0, mp4, to 'mayank_navid_bars_try2.mp4':
  
    Metadata:
  
      encoder         : Lavf58.12.100
  
      Stream #0:0: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        encoder         : Lavc58.18.100 aac
  
      Stream #0:1: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1280x480 [SAR 1:1 DAR 8:3], q=-1--1, 333 fps, 10656 tbn, 333 tbc (default)
  
      Metadata:
  
        encoder         : Lavc58.18.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
  Past duration 0.999992 too large
  
      Last message repeated 12 times
  
  More than 1000 frames duplicated   33280kB time=00:01:08.03 bitrate=4007.4kbits/s dup=982 drop=1590 speed=0.536x    
  
  frame=22679 fps=177 q=-1.0 Lsize=   33892kB time=00:01:08.10 bitrate=4076.9kbits/s dup=1339 drop=1590 speed=0.531x    
  
  video:32804kB audio:953kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.401324%
  
  [aac @ 0x6d4c680] Qavg: 22255.799
  
  [libx264 @ 0x6d21600] frame I:91    Avg QP:15.31  size: 51639
  
  [libx264 @ 0x6d21600] frame P:22588 Avg QP:18.24  size:  1279
  
  [libx264 @ 0x6d21600] mb I  I16..4: 100.0%  0.0%  0.0%
  
  [libx264 @ 0x6d21600] mb P  I16..4:  0.2%  0.0%  0.0%  P16..4: 13.0%  0.0%  0.0%  0.0%  0.0%    skip:86.8%
  
  [libx264 @ 0x6d21600] coded y,uvDC,uvAC intra: 44.9% 54.0% 29.9% inter: 2.0% 10.9% 0.1%
  
  [libx264 @ 0x6d21600] i16 v,h,dc,p: 45% 24% 13% 18%
  
  [libx264 @ 0x6d21600] i8c dc,h,v,p: 51% 20% 18% 11%
  
  [libx264 @ 0x6d21600] kb/s:3945.79