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• FFMPeg generated video : Audio has 'glitches' when uploaded to YouTube

  7 octobre 2023, par CularBytes

  I've generated a voice from Azure AI Speech at 48KHz and 96K Bit Rate, generated a video of some stock footages and I'm trying to combine all of that with a background music.
The voice-over is generated per setence, so that I know how long each setence is and to include relevant video footage.

  


  I'm using FFMpeg through the FFMpegCore nuget package.

  


  The problem

  


  After the video is complete with background music, I play it on my computer and it's perfect (no audio glitches, music keeps playing). But when uploaded to youtube it has 'breaks' in the music inbetween sentences (basically everytime a new voice-fragment is starting).

  


  Example : https://www.youtube.com/watch?v=ieNvQ2TNq44

  


  The code

  


  All of the footage is combined with mostly FFMpeg.Join(string output, string[] videos). These video files also contain the voice-overs (per sentance).

  


  After that I try to add the music like this :

  


     string outputTimelineWithMusicPath = _workingDir + $@"\{videoTitle}_withmusic.mp4";
    FFMpegArguments
        .FromFileInput(inputVideoPath)
        .AddFileInput(musicPath)
        .OutputToFile(outputPath, true, options => options
            .CopyChannel()
            .WithAudioCodec(AudioCodec.Aac)
            .WithAudioBitrate(AudioQuality.Good)
            .UsingShortest(true)
            .WithCustomArgument("-filter_complex \"[0:a]aformat=fltp:44100:stereo,apad[0a];[1]aformat=fltp:44100:stereo,volume=0.05[1a];[0a][1a]amerge[a]\" -map 0:v -map \"[a]\" -ac 2"))
        .ProcessSynchronously();


  


  I've tried to mess around with the CustomArgument, but so far no success.

  


  For example, I thought removing apad from the argument so no 'blank spots' are added, should perhaps fix the issue. Also tried to use amix instead of amerge.

  


  Last try

  


  I've tried to first make sure both files had the same sample rate, in the hope to fix the issue. So far, no success

  


      string outputVideoVoicePath = _workingDir + $@"\{title}_voiceonly_formatting.mp4";
    string musicReplacePath = _workingDir + $@"\{title}_music_formatted.aac";
    FFMpegArguments
    .FromFileInput(inputVideoPath)
    .OutputToFile(outputVideoVoicePath, true, options => options
        .WithAudioCodec(AudioCodec.Aac)
        .WithAudioBitrate(128)
        .WithAudioSamplingRate(44100)
    )
    .ProcessSynchronously();
    
    FFMpegArguments
        .FromFileInput(music.FilePath)
        .OutputToFile(musicReplacePath, true, options => options
            .WithAudioCodec(AudioCodec.Aac)
            .WithAudioBitrate(256) //also tried 96 (which is original format)
            .WithAudioSamplingRate(44100)
        )
        .ProcessSynchronously();
    
    
    Console.WriteLine("Add music...");
    var videoTitle = Regex.Replace(title, "[^a-zA-Z]+", "");
    string outputTimelineWithMusicPath = _workingDir + $@"\{videoTitle}_withmusic.mp4";
    FFMpegArguments
        .FromFileInput(outputVideoVoicePath)
        .AddFileInput(musicReplacePath)
        .OutputToFile(outputTimelineWithMusicPath, true, options => options
            .CopyChannel()
            .WithAudioCodec(AudioCodec.Aac)
            .WithAudioBitrate(AudioQuality.Good)
            .UsingShortest(true)
            .WithCustomArgument("-filter_complex \"[0:a]aformat=fltp:44100:stereo[0a];[1]aformat=fltp:44100:stereo,volume=0.05[1a];[0a][1a]amix=inputs=2[a]\" -map 0:v -map \"[a]\" -ac 2"))
        .ProcessSynchronously();
    return outputTimelineWithMusicPath;


  


  I'm not much of an expert when it comes to audio/video codecs. I do scale each stock video to 24fps, 1920x1080 and the music has a original bitrate of 256Kbps / 44100 sample rate (so I probably don't even have to convert the audio file).

  


• Compressing videos from a smartphone

  21 septembre 2019, par fejesjoco

  I have a Nexus 6p with the stock camera. It’s set to record at 1080p, 30fps. Here’s a 5 second sample (11 MB).

  Videos from this phone come out at about 17 Mbps on average. I tried to compress it with ffmpeg with -c:v libx264 -crf 23 -preset veryslow, the result comes out at about 5.5 MB, which is about 9 Mbps.

  I think this bitrate is a bit too much. When I look at torrent file listings, I can see high quality videos at 3 GB in size on average, and if such a movie is 90 minutes long on average, that is about 4-5 Mbps which sounds okay.

  I’m wondering, why the big difference ? I can notice that my video is noisy/grainy (which is expected from a phone), and that might reduce compressibility. I tried a few ffmpeg filters, like hqdn3d and atadenoise, but the noise mostly remained (maybe I didn’t play with it enough). Then I figured, the video is also shaky (which is also expected), and that might reduce compressibility too (and even makes temporal noise filtering less effective). I tried to stabilize it with the deshake filter, but that didn’t help either.

  I know I could just limit the bandwidth to whatever I like, but there must be a reason why ffmpeg thinks it needs a high bandwidth to maintain a certain quality, and a lower bandwidth would just decrease the quality.

  Why do these videos have such a high bitrate ? What’s the best way to compress them more while keeping or even increasing their quality ?

• Compressing videos from a smartphone

  9 novembre 2016, par fejesjoco

  I have a Nexus 6p with the stock camera. It’s set to record at 1080p, 30fps. Here’s a 5 second sample (11 MB).

  Videos from this phone come out at about 17 Mbps on average. I tried to compress it with ffmpeg with -c:v libx264 -crf 23 -preset veryslow, the result comes out at about 5.5 MB, which is about 9 Mbps.

  I think this bitrate is a bit too much. When I look at torrent file listings, I can see high quality videos at 3 GB in size on average, and if such a movie is 90 minutes long on average, that is about 4-5 Mbps which sounds okay.

  I’m wondering, why the big difference ? I can notice that my video is noisy/grainy (which is expected from a phone), and that might reduce compressibility. I tried a few ffmpeg filters, like hqdn3d and atadenoise, but the noise mostly remained (maybe I didn’t play with it enough). Then I figured, the video is also shaky (which is also expected), and that might reduce compressibility too (and even makes temporal noise filtering less effective). I tried to stabilize it with the deshake filter, but that didn’t help either.

  I know I could just limit the bandwidth to whatever I like, but there must be a reason why ffmpeg thinks it needs a high bandwidth to maintain a certain quality, and a lower bandwidth would just decrease the quality.

  Why do these videos have such a high bitrate ? What’s the best way to compress them more while keeping or even increasing their quality ?