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• avformat/rcwtdec : add RCWT Closed Captions demuxer

  2 avril 2024, par Marth64

  avformat/rcwtdec : add RCWT Closed Captions demuxer
  RCWT (Raw Captions With Time) is a format native to ccextractor,
  
  a commonly used OSS tool for processing 608/708 Closed Captions (CC).
  
  RCWT can be used to archive the original extracted CC bitstream.
  
  The muxer was added in January 2024. In this commit, add the demuxer.
  One can now demux RCWT files for rendering in ccaption_dec or interop
  
  with ccextractor (which produces RCWT). Using the muxer/demuxer combo,
  
  the CC bits can be kept for processing or rendering with either tool.
  
  This can be an effective way to backup an original CC stream, including
  
  format extensions like EIA-708 and overall original presentation.
  Signed-off-by : Marth64 <marth64@proxyid.net>
  

  • [DH] Changelog
  • [DH] doc/demuxers.texi
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/rcwtdec.c

• How can I remove every nth frame from raw video using ffmpeg ?

  15 juin 2024, par DaveB44

  Question moved to SuperUser, please reply there

  


  I have many cine films that have been digitally converted. They have been converted as a 25 fps with 2 frames in every 23 duplicated. I need to remove the duplicated frames using a bitstream filter so there is no decoding/encoding.

  


  After removing the frames I will change to the original cine frame rate of 18 fps. I will then change the frame rate to 25 fps using duplicated frames. I don't want to interpolate as I want to preserve the jerky format of the cine. Finally I will video editing software that will do the final encoding.

  


  All the additional steps will cause several stages of decoding/encoding, that I need to avoid.

  


  First I used a combination of the answers to FFmpeg remove video frames at specific intervals and FFmpeg remove every 6th frame starting from the 3rd frame, on an mp4 file to check it works. I modified it to remove every 4th and 17th frame in 25.

  


  ffmpeg -loglevel warning -i cine.mp4 -an -vf "select='if((mod(n-4,25)),(mod(n-17,25)))',setpts='N/FRAME_RATE/TB'" cine-23.mp4


  


  This works fine, but I end up with a file a quarter the size.

  


  I now used Gyan's answer in Using ffmpeg to change framerate to extract the raw bitstream.

  


  ffmpeg -loglevel warning -i cine.mp4 -c copy -f h264 cine.h264


  


  This created the h264 file as expected, surprisingly it was 16 kB smaller than the original (67 GB file size).

  


  I then modified the code to use the .h264 file.

  


  ffmpeg -loglevel warning -i cine.h264 -vf "select='if((mod(n-4,25)),(mod(n-17,25)))',setpts='N/FRAME_RATE/TB'" cine-23.h264


  


  This gave the following error, but created the cine-23.h264 file although it was the same size as cine-23.mp4 in the test above

  


  [h264 @ 00000245ec0bfb80] non-existing SPS 0 referenced in buffering period
    Last message repeated 1 times


  


  I then checked the ffmpeg bitstream filter documentation and found the bitstream filter setts. I changed my code to the following.

  


  ffmpeg -loglevel warning -i cine.h264 -bsf:v "select='if((mod(n-4,25)),(mod(n-17,25)))',setts=pts='N/FRAME_RATE/TB'" cine-23.h264


  


  Which resulted in the following error.

  


  [vost#0:0/libx264 @ 000002916cf173c0] Error parsing bitstream filter sequence 'select='if((mod(n-4,25)),(mod(n-17,25)))',setts=pts='N/FRAME_RATE/TB'': Bitstream filter not found
Error opening output file cine-23.h264.
Error opening output files: Bitstream filter not found


  


  I'm assuming the error is because setts does not support select. Is there another way to achieve what I am looking for ?

  


  I could use mpdecimate but as that has to compare each frame it is much slower than defining it only needs to delete frames 4 and 17 in every second.

  


  This is the output of ffprobe on my original file.

  


  ffprobe version 2023-11-28-git-47e214245b-full_build-www.gyan.dev Copyright (c) 2007-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58. 32.100 / 58. 32.100
  libavcodec     60. 35.100 / 60. 35.100
  libavformat    60. 18.100 / 60. 18.100
  libavdevice    60.  4.100 / 60.  4.100
  libavfilter     9. 14.100 /  9. 14.100
  libswscale      7.  6.100 /  7.  6.100
  libswresample   4. 13.100 /  4. 13.100
  libpostproc    57.  4.100 / 57.  4.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'cine.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 19529864
    compatible_brands: mp42isom
    creation_time   : 2024-02-19T21:01:10.000000Z
  Duration: 00:01:00.00, start: 0.000000, bitrate: 9245 kb/s
  Stream #0:0[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 720x576 [SAR 35:32 DAR 175:128], 9243 kb/s, 25 fps, 25 tbr, 25 tbn (default)
    Metadata:
      creation_time   : 2024-02-19T21:01:10.000000Z
      handler_name    : Video Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding


  


• Struggling to add subtitles to a video using FFMPEG and C#

  19 mars 2024, par MattHodson

  I'm trying to add subtitles to my videos, 100% with code using FFMPEG and C#.

  


  But I'm getting the following error :

  


  


  ffmpeg version 2024-02-04-git-7375a6ca7b-essentials_build-www.gyan.dev Copyright (c) 2000-2024 the FFmpeg developers
built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
configuration : —enable-gpl —enable-version3 —enable-static —pkg-config=pkgconf —disable-w32threads —disable-autodetect —enable-fontconfig —enable-iconv —enable-gnutls —enable-libxml2 —enable-gmp —enable-bzlib —enable-lzma —enable-zlib —enable-libsrt —enable-libssh —enable-libzmq —enable-avisynth —enable-sdl2 —enable-libwebp —enable-libx264 —enable-libx265 —enable-libxvid —enable-libaom —enable-libopenjpeg —enable-libvpx —enable-mediafoundation —enable-libass —enable-libfreetype —enable-libfribidi —enable-libharfbuzz —enable-libvidstab —enable-libvmaf —enable-libzimg —enable-amf —enable-cuda-llvm —enable-cuvid —enable-ffnvcodec —enable-nvdec —enable-nvenc —enable-dxva2 —enable-d3d11va —enable-libvpl —enable-libgme —enable-libopenmpt —enable-libopencore-amrwb —enable-libmp3lame —enable-libtheora —enable-libvo-amrwbenc —enable-libgsm —enable-libopencore-amrnb —enable-libopus —enable-libspeex —enable-libvorbis —enable-librubberband
libavutil 58. 36.101 / 58. 36.101
libavcodec 60. 38.100 / 60. 38.100
libavformat 60. 20.100 / 60. 20.100
libavdevice 60. 4.100 / 60. 4.100
libavfilter 9. 17.100 / 9. 17.100
libswscale 7. 6.100 / 7. 6.100
libswresample 4. 13.100 / 4. 13.100
libpostproc 57. 4.100 / 57. 4.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C :\Users\Gamer\source\repos\XXXX\bin\Debug\net8.0\ce31c8ab-4b53-44e8-9e25-d02ba5466144\output.mp4' :
Metadata :
major_brand : isom
minor_version : 512
compatible_brands : isomiso2avc1mp41
encoder : Lavf60.20.100
Duration : 00:03:18.84, start : 0.000000, bitrate : 101 kb/s
Stream #0:00x1 : Video : h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1024x1792, 26 kb/s, 1 fps, 1 tbr, 16384 tbn (default)
Metadata :
handler_name : VideoHandler
vendor_id : [0][0][0][0]
encoder : Lavc60.38.100 libx264
Stream #0:10x2 : Audio : aac (LC) (mp4a / 0x6134706D), 24000 Hz, mono, fltp, 74 kb/s (default)
Metadata :
handler_name : SoundHandler
vendor_id : [0][0][0][0]
[Parsed_subtitles_0 @ 000001a87404e3c0] Unable to parse option value "UsersGamersourcereposXXXXbinDebugnet8.0ce31c8ab-4b53-44e8-9e25-d02ba5466144output.srt" as image size
Error applying option 'original_size' to filter 'subtitles' : Invalid argument
[vost#0:0/libx264 @ 000001a874064a40] Error initializing a simple filtergraph
Error opening output file C :\Users\Gamer\source\repos\XXXX\bin\Debug\net8.0\ce31c8ab-4b53-44e8-9e25-d02ba5466144\videoWithSubtitles.mp4.
Error opening output files : Invalid argument

  


  


  It seems to be something related to paths, but I have tried EVERYTHING in my knowledge to fix this, still no luck... spent the majority of the day on it, no luck... so StackOverflow here I come !

  


  My code :

  


     public static async Task AddSubtitlesToVideoAsync(string videoPath, string subtitlesPath, string outputPath)
    {
        if (File.Exists(videoPath) && File.Exists(subtitlesPath))
        {
            //string subtitlesPathForwardSlashes = subtitlesPath.Replace("\\", "/");
            //string ffmpegCommand = $"-i \"{videoPath}\" -filter_complex \"subtitles='{subtitlesPathForwardSlashes}'\" \"{outputPath}\"";
            //string ffmpegCommand = $"-i \"{videoPath}\" -vf subtitles={subtitlesPathForwardSlashes} \"{outputPath}\"";
            //string ffmpegCommand = $"-i \"{videoPath}\" -vf subtitles=\"{subtitlesPath}\" \"{outputPath}\"";
            string subtitlesPathEscaped = subtitlesPath.Replace("\\", "\\\\");
            string ffmpegCommand = $"-i \"{videoPath}\" -vf subtitles=\"{subtitlesPathEscaped}\" \"{outputPath}\"";


            //output    -i C:\Users\Gamer\source\repos\XXXX\bin\Debug\net8.0\d745a08d-b932-47ac-a81c-45e9483590a7\output.mp4 -vf subtitles="C:/Users/Gamer/source/repos/XXXX/bin/Debug/net8.0/d745a08d-b932-47ac-a81c-45e9483590a7/generatedSubtitles.srt" C:\Users\Gamer\source\repos\XXXX\bin\Debug\net8.0\d745a08d-b932-47ac-a81c-45e9483590a7\videoWithSubtitles.mp4
            await ExecuteSubtitleCommandAsync(ffmpegCommand);
        }
        else
        {
            Console.WriteLine("Files can't be found.");
        }
    }

    public static async Task ExecuteSubtitleCommandAsync(string arguments)
    {
        string ffmpegExecutablePath = ffmpegRoot;
        var startInfo = new ProcessStartInfo(ffmpegExecutablePath, arguments)
        {
            CreateNoWindow = true,
            UseShellExecute = false,
            RedirectStandardOutput = true,
            RedirectStandardError = true
        };

        using (var process = new Process { StartInfo = startInfo })
        {
            process.EnableRaisingEvents = true; // Enable the Exited event.
            process.Exited += (sender, e) =>
            {
                Console.WriteLine($"FFmpeg process exited with code {process.ExitCode}.");
            };

            try
            {
                process.Start();
                // Asynchronously read the standard output and standard error of the process
                var outputTask = process.StandardOutput.ReadToEndAsync();
                var errorTask = process.StandardError.ReadToEndAsync();
                // Wait for both asynchronous tasks to complete
                await Task.WhenAll(outputTask, errorTask);

                var output = await outputTask;
                var error = await errorTask;

                if (!string.IsNullOrEmpty(error))
                {
                    Console.WriteLine("FFmpeg error: " + error);
                }
                else
                {
                    Console.WriteLine("FFmpeg process completed successfully.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error: " + ex.Message);
            }
            finally
            {
                // Wait for the process to exit if it hasn't already.
                if (!process.HasExited)
                {
                    process.WaitForExit();
                }
            }
        }
    }