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• lavc : Check codec_whitelist early in avcodec_open2()

  30 juillet 2024, par Dale Curtis

  lavc : Check codec_whitelist early in avcodec_open2()
  This ensures that if a codec isn't on codec_whitelist, trying to open it
  
  will not trigger ff_codec_close(), which could invalidate useful
  
  information still present in the context.
  Signed-off-by : Dale Curtis <dalecurtis@chromium.org>
  
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DH] libavcodec/avcodec.c

• avcodec/h2645_sei : use the RefStruct API for film_grain_characteristics

  25 octobre 2024, par James Almer

  avcodec/h2645_sei : use the RefStruct API for film_grain_characteristics
  And ensure the buffer is synced between threads.
  
  Based on a patch by Dale Curtis <dalecurtis@chromium.org>
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/h2645_sei.c
  • [DH] libavcodec/h2645_sei.h
  • [DH] libavcodec/h264_sei.c
  • [DH] libavcodec/h264_slice.c
  • [DH] libavcodec/hevc/hevcdec.c

• Handling Timestamp Discontinuity and Non-Monotonic DTS Errors When Multiplexing Multiple TV Programs with FFmpeg

  13 août 2024, par the_man

  I'm encountering issues with timestamp discontinuities and non-monotonic DTS errors while attempting to multiplex multiple TV programs from an MPEG-TS input stream using FFmpeg.
The input is a live MPEG-TS stream delivered via UDP.
Information about input from ffmpeg :

  


  Input #0, mpegts, from 'udp://192.168.0.20:1236':
  Duration: N/A, start: 13165.765389, bitrate: N/A
  Program 10352
    Metadata:
      service_name    : MDR Sachsen HD
      service_provider: DD
  Stream #0:1[0x65]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn
  Stream #0:2[0x66](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s
  Stream #0:3[0x67](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s (visual impaired) (descriptions)
  Stream #0:4[0x68](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 192 kb/s (hearing impaired)
  Stream #0:5[0x69](deu): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006), 492x250
  Stream #0:6[0x6a](deu): Audio: ac3 ([6][0][0][0] / 0x0006), 48000 Hz, stereo, fltp, 448 kb/s
  Stream #0:7[0x6b]: Unknown: none ([5][0][0][0] / 0x0005)
  Stream #0:8[0x6c](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  Program 10355
    Metadata:
      service_name    : hr-fernsehen HD
      service_provider: DD
  Stream #0:13[0xc9]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn
  Stream #0:14[0xca](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 192 kb/s
  Stream #0:15[0xcb](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 192 kb/s (visual impaired) (descriptions)
  Stream #0:16[0xcc](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 192 kb/s (hearing impaired)
  Stream #0:9[0xcd](deu): Subtitle: dvb_teletext, 492x250
  Stream #0:17[0xce](deu): Audio: ac3 ([6][0][0][0] / 0x0006), 48000 Hz, 5.1(side), fltp, 448 kb/s
  Stream #0:18[0xcf]: Unknown: none ([5][0][0][0] / 0x0005)
  Stream #0:19[0xd0](deu): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006) (hearing impaired)
  Program 73
    Metadata:
      service_name    : DMAX Austria
      service_provider: DD
  Stream #0:11[0x12e](deu): Subtitle: dvb_teletext, 492x250
  Stream #0:10[0x12d]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv, top first), 544x576 [SAR 32:17 DAR 16:9], 25 fps, 25 tbr, 90k tbn
    Side data:
      cpb: bitrate max/min/avg: 15000000/0/0 buffer size: 1835008 vbv_delay: N/A
  Stream #0:12[0x12f](deu): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 192 kb/s (clean effects)
  Stream #0:20[0x130]: Unknown: none ([5][0][0][0] / 0x0005)
  No Program
  Stream #0:0[0x12]: Data: epg


  


  The goal is : to map several video and audio streams into a single MPEG-TS output while maintaining a constant bitrate (CBR) of 31668449 bps and outputting to a DVB device.

  


  Say if I map one Program (program_num=10352:title="MDR Sachsen HD") with all their streams, like that :

  


  ffmpeg  -i "udp://192.168.0.20:1236?fifo_size=10000000&overrun_nonfatal=1&reconnect=1&reconnect_streamed=1&reconnect_delay_max=2" \
-map 0:v:i:0x65 -map 0:a:i:0x66 -map 0:a:i:0x67 -map 0:a:i:0x68 -map 0:a:i:0x6a \
-program program_num=10352:title="MDR Sachsen HD":st=0:st=1:st=2:st=3:st=4 \
-ignore_unknown \
-c copy -copyts -muxrate 31668449 -f mpegts -y /dev/dvb/adapter0/mod0


  


  It works very well !

  


  But if i try to map multiple programs, each with its own video and audio streams, as follows :

  


  Program 10352 : MDR Sachsen HD

  


  

  • Video : H.264, 1280x720, 50 fps

  


  • Multiple audio streams : MP2 and AC3

  


  


  Program 73 : DMAX Austria

  


  

  • Video : MPEG2, 544x576, 25 fps

  


  • Multiple audio streams : MP2 and AC3

  


  


  I encounter errors like :

  


  

  • Timestamp Discontinuity : Errors indicating mismatches in timestamps
when FFmpeg aligns the streams.

  


  • Non-Monotonic DTS : Warnings about DTS
values not being strictly increasing, leading to potential
synchronization issues.

  


  


  Questions :

  


  

  1. How can I resolve timestamp discontinuities and non-monotonic DTS errors when multiplexing multiple TV channels into a single MPEG-TS stream with FFmpeg ?

  


  2. Are there specific FFmpeg options or settings that can help synchronize streams with different characteristics ?

  


  3. Are there alternative tools or approaches for achieving constant bitrate multiplexing of multiple TV channels that might handle these synchronization issues better ?

  


  


  Any insights or suggestions on handling these errors and successfully multiplex multiple TV channels would be greatly appreciated.

  


  ---

  


  I have tried next options (nothing helps thought ) :

  


  

  • async 1 -vsync 1 -> handle synchronization issues by adjusting the audio and video streams to align better.

  


  • copyts -> (copy timestamps) to preserve original timestamps

  


  • fflags :

    

    • +genpts -> flag tells FFmpeg to generate presentation timestamps (PTS) when they are missing.

    


    • +discardcorrupt -> Discards corrupted frames.

    


    • +igndts -> Ignores DTS (Decoding Time Stamps) if present.

    


    


  


  • avoid_negative_ts make_zero -> Adjusts the timestamps to avoid negative values.

  


  • mpegts_flags : Configures MPEG-TS specific flags for the output.

    

    • +resend_headers : Resends the PAT/PMT headers periodically.

    


    • +pat_pmt_at_frames : Forces PAT/PMT to be sent at the start of frames.

    


    • +latm : Enables LATM (Low-Level Audio Transport Multiplex).

    


    


  


  • pcr_period 20 -> Sets the Periodical PCR (Program Clock Reference) interval in milliseconds.