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• avformat/rtsp : initialize reply1

  8 juin 2024, par Michael Niedermayer

  avformat/rtsp : initialize reply1
  It seems reply1 is initialized by ff_rtsp_send_cmd() in most cases but there
  
  are code paths like "continue" which look like they could skip it but even if not
  
  writing this so a complex loop after several layers of calls initialized a local
  
  variable through a pointer is just bad design.
  
  This patch simply initialized the variable.
  Fixes : CID1473532 Uninitialized scalar variable
  Sponsored-by : Sovereign Tech Fund
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/rtsp.c

• Different container duration between ffmpeg versions which causes audio gaps

  4 septembre 2024, par blits

  I'm trying to make a looped RTMP stream from a single video (in this
example - YouTube), but starting with version 6.0 it introduces a gap in-between loops in the audio which is quite audible. Version before 6.0 (I
tried 5.1.6 and 4.4.2) work as expected and don't introduce any gaps.

  


  The difference I spotted is that the master version (7.0.2) and the 5.1.6, for
example, report a different duration time. Is there any reason why that might happen ?

  


  v5.1.6 :

  


   Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'demo-video.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     creation_time   : 2024-09-03T15:30:51.000000Z
     encoder         : Blackmagic Design DaVinci Resolve Studio
   Duration: 00:00:05.00, start: 0.000000, bitrate: 35440 kb/s


  


  v7.0.2 :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'demo-video.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2024-09-03T15:30:51.000000Z
    encoder         : Blackmagic Design DaVinci Resolve Studio
  Duration: 00:00:05.01, start: 0.000000, bitrate: 35346 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 2560x1440 [SAR 1:1 DAR 16:9], 35240 kb/s, 24 fps, 24 tbr, 12288 tbn (default)
      Metadata:
        creation_time   : 2024-09-03T15:30:51.000000Z
        handler_name    : VideoHandler
        vendor_id       : [0][0][0][0]
        encoder         : H.264 NVIDIA
        timecode        : 01:00:00:00


  


  As you can see, v5.1.6 report duration of 00:00:05.00 (which is correct) and v7.0.2 is 00:00:05.01 (1ms longer), which is what I think is causing the issue (but I'm not so sure about that). The original file is 5 seconds long which is what can be checked by ffprobe as well, but some streams report a 00:05.01 duration time.

  


  I tried to remedy this issue in many different ways by trimming the video/audio, using different flags, like -shortest, but that didn't help in any way - there's still a gap in the audio which is noticeable when looping the video. And like I said versions such as v5.1.6 work fine and there's no such gap.

  


  I guess what changed between versions is how ffmpeg interprets these streams but in the end I spent 2 days trying to avoid gaps in audio when streaming and nothing helped.

  


  How to reproduce :

  


  You can just stream the video in any RTMP destination of your liking, like YouTube and observe that there would be gaps (audio break-ups) in between every 5 seconds (once video ends). Video is accessible through the link from the curl command

  


  curl -o stream-audio-gap-issue.mp4 https://r2v.streamloop.app/obj_01j6y0pk83fy8vp06a9mmkkqah.mp4
ffmpeg -re -stream_loop -1 -i stream-audio-gap-issue.mp4 -c copy -f flv rtmp://a.rtmp.youtube.com/live2/[your-key]


  


  Expected : there are no gaps every 5 seconds, like in old versions of ffmpeg

  


  Instead : there are tiny audio gaps which are quite noticable

  


  ffprobe outputs is available on gist : https://gist.github.com/blitss/1e221b4fa8885b1df8ac2096746239cf

  


  I'm looking for literally any workarounds that will help avoid audio gaps whilst still preserving the latest version of ffmpeg.

  


• Transcoding/ Converting mpeg to h264 using ffmpeg h264_nvenc

  15 septembre 2024, par Mustafa

  I'm trying to transcode a video rendered by Davinci Resolve, using ffmpeg from mpeg4 to h264, on Ubuntu, using the following command.

  


  ffmpeg -y -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -i input.mov -c:a copy -c:v h264_nvenc -b:v 8M -preset 7 output-h264_nvenc-p7.mp4 -v verbose


  


  And my Nvidia card is NVIDIA GeForce GTX 1650.

  


  I'm gettting the following error :

  


  [mpeg4 @ 0x55a893ed3200] Video width 3840 not within range from 48 to 2032
[mpeg4 @ 0x55a893ed3200] Failed setup for format cuda: hwaccel initialisation returned error.


  


  And here's the complete output. The command produces an output but its quality is significantly less than the original.

  


    built with gcc 13 (Ubuntu 13.2.0-23ubuntu4)
  configuration: --enable-nonfree --enable-cuda-nvcc --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64 --disable-static --enable-shared --enable-gpl --enable-libx264
  libavutil      59. 36.100 / 59. 36.100
  libavcodec     61. 13.100 / 61. 13.100
  libavformat    61.  5.101 / 61.  5.101
  libavdevice    61.  2.101 / 61.  2.101
  libavfilter    10.  2.102 / 10.  2.102
  libswscale      8.  2.100 /  8.  2.100
  libswresample   5.  2.100 /  5.  2.100
  libpostproc    58.  2.100 / 58.  2.100
-vsync is deprecated. Use -fps_mode
Passing a number to -vsync is deprecated, use a string argument as described in the manual.
Selecting decoder 'mpeg4' because of requested hwaccel method cuda
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    creation_time   : 2024-09-15T04:25:29.000000Z
    encoder         : Blackmagic Design DaVinci Resolve
  Duration: 00:20:34.87, start: 0.000000, bitrate: 347243 kb/s
  Stream #0:0[0x1]: Video: mpeg4 (Simple Profile), 1 reference frame (mp4v / 0x7634706D), yuv420p(bt709/bt709/unknown, left), 3840x2160 [SAR 1:1 DAR 16:9], 345703 kb/s, 60 fps, 60 tbr, 15360 tbn (default)
      Metadata:
        creation_time   : 2024-09-15T04:25:29.000000Z
        handler_name    : VideoHandler
        vendor_id       :     
        encoder         : MPEG4 Video
        timecode        : 01:00:00:00
  Stream #0:1[0x2]: Audio: pcm_s16le (lpcm / 0x6D63706C), 48000 Hz, stereo, s16, 1536 kb/s (default)
      Metadata:
        creation_time   : 2024-09-15T04:25:29.000000Z
        handler_name    : SoundHandler
        vendor_id       : [0][0][0][0]
  Stream #0:2[0x3](eng): Data: none (tmcd / 0x64636D74) (default)
      Metadata:
        creation_time   : 2024-09-15T04:25:29.000000Z
        handler_name    : TimeCodeHandler
        timecode        : 01:00:00:00
[out#0/mp4 @ 0x55a8929e8d80] No explicit maps, mapping streams automatically...
[vost#0:0/h264_nvenc @ 0x55a8929f5880] Created video stream from input stream 0:0
[aost#0:1/copy @ 0x55a893867080] Created audio stream from input stream 0:1
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg4 (native) -> h264 (h264_nvenc))
  Stream #0:1 -> #0:1 (copy)
[vost#0:0/h264_nvenc @ 0x55a8929f5880] Starting thread...
[vf#0:0 @ 0x55a8929f17c0] Starting thread...
[vist#0:0/mpeg4 @ 0x55a89293a100] [dec:mpeg4 @ 0x55a8929f4440] Starting thread...
[in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 0x55a8929e0600] Starting thread...
Press [q] to stop, [?] for help
[mpeg4 @ 0x55a893ed3200] NVDEC capabilities:
[mpeg4 @ 0x55a893ed3200] format supported: yes, max_mb_count: 8192
[mpeg4 @ 0x55a893ed3200] min_width: 48, max_width: 2032
[mpeg4 @ 0x55a893ed3200] min_height: 16, max_height: 2032
[mpeg4 @ 0x55a893ed3200] Video width 3840 not within range from 48 to 2032
[mpeg4 @ 0x55a893ed3200] Failed setup for format cuda: hwaccel initialisation returned error.
[graph -1 input from stream 0:0 @ 0x75c970002e40] w:3840 h:2160 pixfmt:yuv420p tb:1/15360 fr:60/1 sar:1/1 csp:bt709 range:unknown
[graph -1 input from stream 0:0 @ 0x75c970002e40] video frame properties congruent with link at pts_time: 0
[h264_nvenc @ 0x55a8929e62c0] Using device cuda0 (type cuda) with h264_nvenc encoder.
[h264_nvenc @ 0x55a8929e62c0] Loaded Nvenc version 12.2
[h264_nvenc @ 0x55a8929e62c0] Nvenc initialized successfully
[h264_nvenc @ 0x55a8929e62c0] The selected preset is deprecated. Use p1 to p7 + -tune or fast/medium/slow.
Output #0, mp4, to 'output-h264_nvenc-p7.mp4':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf61.5.101
  Stream #0:0: Video: h264 (Main), 1 reference frame (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/unknown, progressive, left), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 8000 kb/s, 60 fps, 15360 tbn (default)
      Metadata:
        creation_time   : 2024-09-15T04:25:29.000000Z
        handler_name    : VideoHandler
        vendor_id       :     
        timecode        : 01:00:00:00
        encoder         : Lavc61.13.100 h264_nvenc
      Side data:
        cpb: bitrate max/min/avg: 0/0/8000000 buffer size: 16000000 vbv_delay: N/A
  Stream #0:1: Audio: pcm_s16le (ipcm / 0x6D637069), 48000 Hz, stereo, s16, 1536 kb/s (default)
      Metadata:
        creation_time   : 2024-09-15T04:25:29.000000Z
        handler_name    : SoundHandler
        vendor_id       : [0][0][0][0]


  


  How can I find the cause of the error and resolve it ?

  


  Also is there a way to improve the quality of the output video as it's much lower than the original ? I tried doing the same conversion using libxh264 (using the CPU) and that produced a far better video.