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• How can i specify range of frames in ffmpeg shuffleframes filter [closed]

  26 juillet 2022, par liphone

  I need to duplicate a bunch of seconds in video and in official docs you can only input frames into shuffleframes filter like so

  


  ffmpeg -i  INPUT -vf "shuffleframes=0 1 2 3 4 5 6 7 ... 592 593 594 595 596 597 598 599 600" OUTPUT


  


  Is there any way to put it like in array ? Or maybe other method of shuffling frames in ffmpeg

  


• How do I redirect the output of SpeechSynthesizer to a Process of ffmpeg

  27 septembre 2020, par TheOneAndOnlyMrX

  I am trying to have a SpeechSynthesizer generate some audio data, pipe it into a Process of FFmpeg, and have FFmpeg save the data to a file (output.wav). Eventually, the audio data will be used for something else, which is why I am using FFmpeg.

  


  using (MemoryStream voiceStream = new MemoryStream())
        using (Process ffmpeg = new Process())
        {
            SpeechSynthesizer synth = new SpeechSynthesizer();

            int samplesPerSecond = 48000;
            int bitsPerSample = 8;
            int channelCount = 2;
            int averageBytesPerSecond = samplesPerSecond * (bitsPerSample / 8) * channelCount;
            int blockalign = (bitsPerSample / 8) * channelCount;
            byte[] formatSpecificData = new byte[0];

            synth.SetOutputToAudioStream(
                voiceStream,
                new System.Speech.AudioFormat.SpeechAudioFormatInfo(
                    System.Speech.AudioFormat.EncodingFormat.Pcm,
                    samplesPerSecond,
                    bitsPerSample,
                    channelCount,
                    averageBytesPerSecond,
                    blockalign,
                    formatSpecificData
                    )
                );

            synth.Speak("Hello there");

            synth.SetOutputToNull();

            ffmpeg.StartInfo = new ProcessStartInfo
            {
                FileName = "ffmpeg",
                Arguments = $"-y -f u8 -ac 2 -ar 48000 -i pipe:0 out.wav",
                UseShellExecute = false,
                RedirectStandardOutput = true,
                RedirectStandardInput = true
            };

            ffmpeg.Start();

            using (Stream ffmpegIn = ffmpeg.StandardInput.BaseStream)
            {
                voiceStream.CopyTo(ffmpegIn);
                
                ffmpegIn.FlushAsync();
            }
        }


  


  When running the program, FFmpeg said that the input stream contains no data, and returns an empty file.
I believe that I do not interface properly with the Process object, however, the problem might also be my incorrect specification of the audio stream, since I do not know much about audio.

  


• what is AV_SAMPLE_FMT_FLT

  21 décembre 2020, par Golu

  SwrContext *swr_ctx = swr_alloc_set_opts(NULL,                          
                        AV_CH_LAYOUT_STEREO,
                        AV_SAMPLE_FMT_FLT,
                        sample_rate,
                        pCodecParameters->channel_layout,                                                                               
                  
                        pCodecParameters->format,
                        pCodecParameters->sample_rate,                          
                        0,
                        NULL);


  


  what exactly AV_SAMPLE_FMT_FLT is ? i already read docs but i want to know that what is float layout means in the context of Audio. How actually binary data of audio will look in that format.