Render Waveform for Region of Audio File

[psideas]

Is there a way to render a waveform based upon a region of an audio file (denoted by a startOffset and endOffset) as opposed to the entire audio file? If so, could you provide the code modifications?

[Mark Heath]

it uses an AudioFileReader, so you can jump in that file with CurrentTime and you can limit the duration with the Take extension method.

reader.CurrentTime = TimeSpan.FromSeconds(30);
peakProvider.Init(reader.Take(TimeSpan.FromSeconds(20)), samplesPerPixel * stepSize);

[LunevNF]

it uses an AudioFileReader, so you can jump in that file with CurrentTime and you can limit the duration with the Take extension method.

reader.CurrentTime = TimeSpan.FromSeconds(30);
peakProvider.Init(reader.Take(TimeSpan.FromSeconds(20)), samplesPerPixel * stepSize);

Hi. Not working. "Init" creates new reader with default startTime!

             AudioFileReader reader = new AudioFileReader(audioFilePath);

            // 1. Конфигурация провайдеров
            //OffsetSampleProvider offsetSampleProvider = new OffsetSampleProvider(reader);

            MaxPeakProvider maxPeakProvider = new MaxPeakProvider();
            RmsPeakProvider rmsPeakProvider = new RmsPeakProvider(200);
            SamplingPeakProvider samplingPeakProvider = new SamplingPeakProvider(200);
            AveragePeakProvider averagePeakProvider = new AveragePeakProvider(4);

            // 2. Конфигурация стиля шкалы
            StandardWaveFormRendererSettings myRendererSettings = new StandardWaveFormRendererSettings();
            myRendererSettings.Width = waveFormWidth;
            myRendererSettings.TopHeight = formTopHeight;
            myRendererSettings.BottomHeight = formBottomHeight;

            // 3. Формирование изображения со шкалой
            WaveFormRenderer renderer = new WaveFormRenderer();

            reader.CurrentTime = TimeSpan.FromSeconds(startMediaSecond);                
            averagePeakProvider.Init(reader.Take(TimeSpan.FromSeconds(endMediaSecond - startMediaSecond)), 200);                

            image = renderer.Render(audioFilePath, averagePeakProvider, myRendererSettings); 

[LunevNF]

I append one function to this lib. Why you don't do it yet - I don't understand

[LunevNF]

        public Image RenderWithTake(string selectedFile, IPeakProvider peakProvider, 
            WaveFormRendererSettings settings, int startFromSeconds, int duration )
        {
            using (var reader = new AudioFileReader(selectedFile))
            {
                reader.CurrentTime = TimeSpan.FromSeconds(startFromSeconds);

                int bytesPerSample = (reader.WaveFormat.BitsPerSample / 8);
                var samples = reader.Length / (bytesPerSample);
                var samplesPerPixel = (int)(samples / settings.Width);
                var stepSize = settings.PixelsPerPeak + settings.SpacerPixels;
                peakProvider.Init(reader.Take(TimeSpan.FromSeconds(duration)), samplesPerPixel * stepSize);
                return Render(peakProvider, settings);
            }
        }

[LunevNF]

Wrong draw:

1. start from 0 second to normal 1 min 59 sec
2. start from not 0 second. No Fill.

[LunevNF]

Okay. This:
peakProvider.Init(reader.Take(TimeSpan.FromSeconds(duration)), samplesPerPixel * stepSize);
Contains empty peaks in the end. That's why it draws empty.
How to remove this empty peaks? "Init" creates peakProvider with full length

[jandito]

error me sale al usar StandardWaveFormRendererSettings(); error ayuda por favor

[LunevNF]

Which error? Show the full error info from IDE?