public static WavePeakData GenerateEmptyPeaks(string peakFileName, int totalSeconds)
{
int peaksPerSecond = Configuration.Settings.VideoControls.WaveformMinimumSampleRate;
var peaks = new List <WavePeak>
{
new WavePeak(1000, -1000)
};
var totalPeaks = peaksPerSecond * totalSeconds;
for (int i = 0; i < totalPeaks; i++)
{
peaks.Add(new WavePeak(1, -1));
}
peaks.Add(new WavePeak(1000, -1000));
// save results to file
using (var stream = File.Create(peakFileName))
{
WaveHeader.WriteHeader(stream, peaksPerSecond, 2, 16, peaks.Count);
byte[] buffer = new byte[4];
foreach (var peak in peaks)
{
WriteValue16Bit(buffer, 0, peak.Max);
WriteValue16Bit(buffer, 2, peak.Min);
stream.Write(buffer, 0, 4);
}
}
return(new WavePeakData(peaksPerSecond, peaks));
}
public static void WriteWaveformData(Stream stream, int sampleRate, List <WavePeak> peaks)
{
WaveHeader.WriteHeader(stream, sampleRate, 2, 16, peaks.Count);
var buffer = new byte[4];
foreach (var peak in peaks)
{
WriteValue16Bit(buffer, 0, peak.Max);
WriteValue16Bit(buffer, 2, peak.Min);
stream.Write(buffer, 0, 4);
}
}
/// <summary>
/// Generates peaks and saves them to disk.
/// </summary>
/// <param name="delayInMilliseconds">Delay in milliseconds (normally zero)</param>
/// <param name="peakFileName">Path of the output file</param>
public WavePeakData GeneratePeaks(int delayInMilliseconds, string peakFileName)
{
int peaksPerSecond = Math.Min(Configuration.Settings.VideoControls.WaveformMinimumSampleRate, _header.SampleRate);
// ensure that peaks per second is a factor of the sample rate
while (_header.SampleRate % peaksPerSecond != 0)
{
peaksPerSecond++;
}
int delaySampleCount = (int)(_header.SampleRate * (delayInMilliseconds / TimeCode.BaseUnit));
// ignore negative delays for now (pretty sure it can't happen in mkv and some places pass in -1 by mistake)
delaySampleCount = Math.Max(delaySampleCount, 0);
var peaks = new List <WavePeak>();
var readSampleDataValue = GetSampleDataReader();
float sampleAndChannelScale = (float)GetSampleAndChannelScale();
long fileSampleCount = _header.LengthInSamples;
long fileSampleOffset = -delaySampleCount;
int chunkSampleCount = _header.SampleRate / peaksPerSecond;
byte[] data = new byte[chunkSampleCount * _header.BlockAlign];
float[] chunkSamples = new float[chunkSampleCount * 2];
_stream.Seek(_header.DataStartPosition, SeekOrigin.Begin);
// for negative delays, skip samples at the beginning
if (fileSampleOffset > 0)
{
_stream.Seek(fileSampleOffset * _header.BlockAlign, SeekOrigin.Current);
}
while (fileSampleOffset < fileSampleCount)
{
// calculate how many samples to skip at the beginning (for positive delays)
int startSkipSampleCount = 0;
if (fileSampleOffset < 0)
{
startSkipSampleCount = (int)Math.Min(-fileSampleOffset, chunkSampleCount);
fileSampleOffset += startSkipSampleCount;
}
// calculate how many samples to read from the file
long fileSamplesRemaining = fileSampleCount - Math.Max(fileSampleOffset, 0);
int fileReadSampleCount = (int)Math.Min(fileSamplesRemaining, chunkSampleCount - startSkipSampleCount);
// read samples from the file
if (fileReadSampleCount > 0)
{
int fileReadByteCount = fileReadSampleCount * _header.BlockAlign;
_stream.Read(data, 0, fileReadByteCount);
fileSampleOffset += fileReadSampleCount;
int chunkSampleOffset = 0;
int dataByteOffset = 0;
while (dataByteOffset < fileReadByteCount)
{
float valuePositive = 0F;
float valueNegative = -0F;
for (int iChannel = 0; iChannel < _header.NumberOfChannels; iChannel++)
{
var v = readSampleDataValue(data, ref dataByteOffset);
if (v < 0)
{
valueNegative += v;
}
else
{
valuePositive += v;
}
}
chunkSamples[chunkSampleOffset] = valueNegative * sampleAndChannelScale;
chunkSampleOffset++;
chunkSamples[chunkSampleOffset] = valuePositive * sampleAndChannelScale;
chunkSampleOffset++;
}
}
// calculate peaks
peaks.Add(CalculatePeak(chunkSamples, fileReadSampleCount * 2));
}
// save results to file
using (var stream = File.Create(peakFileName))
{
WaveHeader.WriteHeader(stream, peaksPerSecond, 2, 16, peaks.Count);
byte[] buffer = new byte[4];
foreach (var peak in peaks)
{
WriteValue16Bit(buffer, 0, peak.Max);
WriteValue16Bit(buffer, 2, peak.Min);
stream.Write(buffer, 0, 4);
}
}
return(new WavePeakData(peaksPerSecond, peaks));
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="stream">Stream of a wave file</param>
public WavePeakGenerator(Stream stream)
{
_stream = stream;
_header = new WaveHeader(_stream);
}
