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• How can I convert a mp4 into an ogv with ffmpeg ? I am getting a "segmentation fault"

  8 mars 2020, par xrainbowuk

  I am trying to use ffmpeg to convert a mp4 video into an ogv and a webm. I am using a Mac and this is what I am putting into the terminal :

  ffmpeg -i "Hands-typing-(mobile-1080p-loop) copy.mp4" -codec:v libtheora -codec:a libvorbis -f ogv output.ogv

  This is what I am getting in response :

      ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with Apple clang version 11.0.0 (clang-1100.0.33.17)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Hands-typing-(mobile-1080p-loop) copy.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42mp41
  
      creation_time   : 2020-03-04T20:14:21.000000Z
  
    Duration: 00:00:21.18, start: 0.000000, bitrate: 8201 kb/s
  
      Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 8085 kb/s, 30 fps, 30 tbr, 30k tbn, 60k tbc (default)
  
      Metadata:
  
        creation_time   : 2020-03-04T20:14:21.000000Z
  
        handler_name    : ?Mainconcept Video Media Handler
  
        encoder         : AVC Coding
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 125 kb/s (default)
  
      Metadata:
  
        creation_time   : 2020-03-04T20:14:21.000000Z
  
        handler_name    : #Mainconcept MP4 Sound Media Handler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> theora (libtheora))
  
    Stream #0:1 -> #0:1 (aac (native) -> vorbis (libvorbis))
  
  Press [q] to stop, [?] for help
  
  zsh: segmentation fault  ffmpeg -i "Hands-typing-(mobile-1080p-loop) copy.mp4" -codec:v libtheora   -f

  I have also tried this, which doesn’t work :

  ffmpeg -i "Hands-typing-(mobile-1080p-loop) copy.mp4" -codec:v libtheora -qscale:v 3 -codec:a libvorbis \
  
    -qscale:a 3 -f ogv output.ogv

  I am struggling to find the answer to my question. Especially as there are so many posts about "segmentation faults".

  Any help is very much appreciated.

• ffmpeg mp3 chunk to wav chunk adds gap in the start of the audio

  13 décembre 2023, par 1Mayur

  I have an mp3 streaming from a URL, I save the chunks in 1024 byes buffer size.
After I get all the chunks, I'm using ffmpeg to convert the incoming mp3 chunk (22050 mono) to a wav chunk.

  


  When I open/play the wav chunk I see that there is an empty gap at the start of every chunk.

  


  here is the code I'm running in Python subprocess in a loop for all the saved chunks

  


  subprocess.run(["ffmpeg", "-i",
    f"{Path.cwd()}/input/{path}",
    f"{Path.cwd()}/temp_output/{path.replace('.mp3', '')}.wav"
])


  


  here is the output in the terminal

  


  processing: test-016.mp3
ffmpeg version 6.0 Copyright (c) 2000-2023 the FFmpeg developers
  built with Apple clang version 15.0.0 (clang-1500.0.40.1)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/6.0_1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
[mp3 @ 0x7fd48e104480] Format mp3 detected only with low score of 25, misdetection possible!
[mp3 @ 0x7fd48e104480] Skipping 463 bytes of junk at 0.
[mp3 @ 0x7fd48e104480] Estimating duration from bitrate, this may be inaccurate
Input #0, mp3, from '/Users/mayur/Projects/input/test-016.mp3':
  Duration: 00:00:00.39, start: 0.000000, bitrate: 169 kb/s
  Stream #0:0: Audio: mp3, 22050 Hz, mono, fltp, 160 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (mp3float) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, wav, to '/Users/mayur/Projects/temp_output/test-016.wav':
  Metadata:
    ISFT            : Lavf60.3.100
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, mono, s16, 352 kb/s
    Metadata:
      encoder         : Lavc60.3.100 pcm_s16le
size=      17kB time=00:00:00.36 bitrate= 379.7kbits/s speed= 253x    
video:0kB audio:17kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.451389%


  


  I tried the pydub as well and faced similar issue.

  


• FFmpeg decode video to lossless frames hardware acceleration CUDA

  29 décembre 2020, par Seva Safris

  I have 1 second H.265-encoded videos at 30 fps coming into a server for processing. The server needs to decode the videos into individual frames (lossless). These videos are coming in very quickly, so performance is of utmost importance. The server has a H.265 compatible Nvidia GPU, and I have built ffmpeg with support for CUDA. The following is the configuration output from ffmpeg :

  


  ffmpeg version N-100479-gd67c6c7f6f Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Ubuntu 8.4.0-3ubuntu2)
  configuration: --enable-nonfree --enable-cuda-nvcc --enable-nvenc --enable-opencl --enable-shared
                 --enable-pthreads --enable-version3 --enable-avresample --enable-ffplay --enable-gnutls
                 --enable-gpl --disable-libaom --disable-libbluray --disable-libdav1d 
                 --disable-libmp3lame --enable-libopus --disable-librav1e --enable-librubberband
                 --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora
                 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264
                 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig
                 --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb
                 --enable-libopencore-amrwb --disable-libopenjpeg --enable-librtmp --enable-libspeex
                 --enable-libsoxr --disable-videotoolbox --disable-libjack --disable-indev=jack
                 --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64


  


  I decode the videos into PNGs, and am using the following command :

  


  ffmpeg -y -vsync 0 -hwaccel cuvid -hwaccel_output_format cuda -hwaccel_device 0 -c:v hevc_cuvid \
       -i 0.mp4 -vf hwdownload,format=nv12 -q:v 1 -qmin 1 -qmax 1 -start_number 0 f%d.png


  


  This command successfully leverages the hardware acceleration for the H.265 decode. But, the PNG encode is done by the CPU.

  


  Does CUDA have support for encoding of lossless images ? The format does not need to be PNG, but it does need to be lossless. CUDA has a nvJPEG Library, but JPEG is a lossy format. Is there a similar image encoding library in CUDA for a lossless format (that is also integrated with ffmpeg) ?

  


  Edit : Some more context....

  


  I am currently using PNGs because of their compression-ability. These images are 2560x1280 in size, btw. On one hand, it is this compression that costs the CPU cycles. On the other hand, I am also limited by the throughput of how fast (and how much aggregate data) can I upload these frames to the upstream consumer. So it's basically a tradeoff between :

  


  

  1. We want to extract these frames as quickly as possible.

  


  2. We want efficiency regarding the image size.