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• 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 ignores set bitrate

  13 mars 2023, par col__panic

  I have a folder of h264 files I am trying to convert to hevc with a lower bitrate set with -b:v flag. For context I am using python running in a Docker container. The issue is that when ffmpeg completes, the output bitrate is extremely low.

  


  As you can see from the ffmpeg command below, I am expecting around 900k bitrate. But as the command runs, it shows around 18k bitrate.

  


  ffmpeg -y -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -i /tmp/input.ts -an -c:v hevc_nvenc -b:v 914k -b_ref_mode 0 -tag:v hvc1 /tmp/output.mp4 
ffmpeg version N-109685-gac37b2c2b1 Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.4.0-1ubuntu1~20.04.1)
  configuration: --enable-nonfree --enable-cuda-nvcc --enable-libnpp --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64
  libavutil      57. 44.100 / 57. 44.100
  libavcodec     59. 58.100 / 59. 58.100
  libavformat    59. 36.100 / 59. 36.100
  libavdevice    59.  8.101 / 59.  8.101
  libavfilter     8. 54.100 /  8. 54.100
  libswscale      6.  8.112 /  6.  8.112
  libswresample   4.  9.100 /  4.  9.100
-vsync is deprecated. Use -fps_mode
Passing a number to -vsync is deprecated, use a string argument as described in the manual.
Input #0, mpegts, from '/tmp/input.ts':
  Duration: 01:04:53.85, start: 85937.219044, bitrate: 2613 kb/s
  Program 1 
  Stream #0:0[0x101]: Video: h264 (Constrained Baseline) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720, 90k tbr, 90k tbn
  Stream #0:1[0x202]: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 130 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> hevc (hevc_nvenc))
Press [q] to stop, [?] for help
Output #0, mp4, to '/tmp/output.mp4':
  Metadata:
    encoder         : Lavf59.36.100
  Stream #0:0: Video: hevc (Main) (hvc1 / 0x31637668), cuda(progressive), 1280x720, q=2-31, 914 kb/s, 90k fps, 90k tbn
    Metadata:
      encoder         : Lavc59.58.100 hevc_nvenc
    Side data:
      cpb: bitrate max/min/avg: 0/0/914000 buffer size: 1828000 vbv_delay: N/A
frame=113118 fps=412 q=49.0 Lsize=    8925kB time=01:04:53.82 bitrate=  18.8kbits/s speed=14.2x    
video:8215kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 8.636624%


  


  And then checking the output shows that it is around 18kb/s.

  


  ffmpeg -i /tmp/output.mp4 
...
  Duration: 01:04:53.82, start: 0.000000, bitrate: 18 kb/s


  


  For reference the input file is 2600kb/s.

  


  ffmpeg -i /tmp/input.ts 
...
  Duration: 01:04:53.85, start: 85937.219044, bitrate: 2613 kb/s



  


  This seems like an issue with the file itself, given that I have run the same command and had it work. Also note that even when I leave out the -b:v flag, the output is about the same.

  


  I have tried setting -minrate:v -maxrate:v -bufsize:v and -ss 00:00:00 flags as well and they did not help.

  


  Also there was another post that mentioned the audio track being an issue and to rule that out, I tried using -an and that didn't help either.

  


  I saw another post that mentioned the order of the parameters being an issue but I don't think that's the issue because this same command has run successfully on other input files.

  


  Any ideas ?

  


  EDIT :
nvm fixed it

  


• FFmpeg bug with a image that has a #ededed color

  11 avril 2023, par Денис Выхрыстюк

  I want to generate a video from images. When the pictures have a gray(#ededed) background then a strange error occurs, but when with other colors everything is good.

  


  I will be grateful for any help.

  


  I run the following commands :

  


  ./ffmpeg.exe -s 1080x1080 -framerate 1 -i ./scene0_%6d.png -crf 1 -c:v rawvideo -pix_fmt yuv420p ./result.yuv


  


  ./ffmpeg.exe -s 1080x1080 -framerate 1 -i ./result.yuv -c:v libx264 -crf 15 -preset veryslow -pix_fmt yuv420p -maxrate 900M -bufsize 12000k ./final.mp4


  


  Result :

  


  Error: Option framerate not found


  


  FFmpeg version :

  


  ffmpeg version N-110165-g9a245bdf5d-20230403 Copyright (c) 2000-2023 the FFmpeg developersbuilt with gcc 12.2.0 (crosstool-NG 1.25.0.152_89671bf)configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-libxml2 --enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libvorbis --enable-opencl --disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-libkvazaar --enable-libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librist --enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-lv2 --disable-libmfx --enable-libvpl --enable-openal --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --disable-vaapi --enable-libvidstab --enable-vulkan --enable-libshaderc --enable-libplacebo --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-ldexeflags= --extra-libs=-lgomp --extra-version=20230403 libavutil 58. 5.100 / 58. 5.100 libavcodec 60. 9.100 / 60. 9.100 libavformat 60. 4.101 / 60. 4.101 libavdevice 60. 2.100 / 60. 2.100 libavfilter 9. 5.100 / 9. 5.100 libswscale 7. 2.100 / 7. 2.100 libswresample 4. 11.100 / 4. 11.100libpostproc 57. 2.100 / 57. 2.100


  


  

  


  I tried other colors and everything is fine. I expect that I will be able to combine the gray images to the video and that the desired color profile will be finded