/// <inheritdoc />
public override bool MaterializeFrame(MediaFrame input, ref MediaBlock output, MediaBlock previousBlock)
{
if (output == null)
{
output = new AudioBlock();
}
if (input is AudioFrame == false || output is AudioBlock == false)
{
throw new ArgumentNullException($"{nameof(input)} and {nameof(output)} are either null or not of a compatible media type '{MediaType}'");
}
var source = (AudioFrame)input;
var target = (AudioBlock)output;
// Create the source and target audio specs. We might need to scale from
// the source to the target
var sourceSpec = FFAudioParams.CreateSource(source.Pointer);
var targetSpec = FFAudioParams.CreateTarget(source.Pointer);
// Initialize or update the audio scaler if required
if (Scaler == null || LastSourceSpec == null || FFAudioParams.AreCompatible(LastSourceSpec, sourceSpec) == false)
{
Scaler = ffmpeg.swr_alloc_set_opts(
Scaler,
targetSpec.ChannelLayout,
targetSpec.Format,
targetSpec.SampleRate,
sourceSpec.ChannelLayout,
sourceSpec.Format,
sourceSpec.SampleRate,
0,
null);
RC.Current.Add(Scaler);
ffmpeg.swr_init(Scaler);
LastSourceSpec = sourceSpec;
}
// Allocate the unmanaged output buffer and convert to stereo.
int outputSamplesPerChannel;
if (target.Allocate(targetSpec.BufferLength) &&
target.TryAcquireWriterLock(out var writeLock))
{
using (writeLock)
{
var outputBufferPtr = (byte *)target.Buffer;
// Execute the conversion (audio scaling). It will return the number of samples that were output
outputSamplesPerChannel = ffmpeg.swr_convert(
Scaler,
&outputBufferPtr,
targetSpec.SamplesPerChannel,
source.Pointer->extended_data,
source.Pointer->nb_samples);
}
}
else
{
return(false);
}
// Compute the buffer length
var outputBufferLength =
ffmpeg.av_samples_get_buffer_size(null, targetSpec.ChannelCount, outputSamplesPerChannel, targetSpec.Format, 1);
// Flag the block if we have to
target.IsStartTimeGuessed = source.HasValidStartTime == false;
// Try to fix the start time, duration and End time if we don't have valid data
if (source.HasValidStartTime == false && previousBlock != null)
{
// Get timing information from the previous block
target.StartTime = TimeSpan.FromTicks(previousBlock.EndTime.Ticks + 1);
target.Duration = source.Duration.Ticks > 0 ? source.Duration : previousBlock.Duration;
target.EndTime = TimeSpan.FromTicks(target.StartTime.Ticks + target.Duration.Ticks);
}
else
{
// We set the target properties directly from the source
target.StartTime = source.StartTime;
target.Duration = source.Duration;
target.EndTime = source.EndTime;
}
target.CompressedSize = source.CompressedSize;
target.SamplesBufferLength = outputBufferLength;
target.ChannelCount = targetSpec.ChannelCount;
target.SampleRate = targetSpec.SampleRate;
target.SamplesPerChannel = outputSamplesPerChannel;
target.StreamIndex = input.StreamIndex;
return(true);
}
/// <summary>
/// Converts decoded, raw frame data in the frame source into a a usable frame. <br />
/// The process includes performing picture, samples or text conversions
/// so that the decoded source frame data is easily usable in multimedia applications
/// </summary>
/// <param name="input">The source frame to use as an input.</param>
/// <param name="output">The target frame that will be updated with the source frame. If null is passed the frame will be instantiated.</param>
/// <param name="siblings">The sibling blocks that may help guess some additional parameters for the input frame.</param>
/// <returns>
/// Return the updated output frame
/// </returns>
/// <exception cref="ArgumentNullException">input</exception>
public override MediaBlock MaterializeFrame(MediaFrame input, ref MediaBlock output, List <MediaBlock> siblings)
{
if (output == null)
{
output = new AudioBlock();
}
var source = input as AudioFrame;
var target = output as AudioBlock;
if (source == null || target == null)
{
throw new ArgumentNullException($"{nameof(input)} and {nameof(output)} are either null or not of a compatible media type '{MediaType}'");
}
// Create the source and target ausio specs. We might need to scale from
// the source to the target
var sourceSpec = FFAudioParams.CreateSource(source.Pointer);
var targetSpec = FFAudioParams.CreateTarget(source.Pointer);
// Initialize or update the audio scaler if required
if (Scaler == null || LastSourceSpec == null || FFAudioParams.AreCompatible(LastSourceSpec, sourceSpec) == false)
{
Scaler = ffmpeg.swr_alloc_set_opts(
Scaler,
targetSpec.ChannelLayout,
targetSpec.Format,
targetSpec.SampleRate,
sourceSpec.ChannelLayout,
sourceSpec.Format,
sourceSpec.SampleRate,
0,
null);
RC.Current.Add(Scaler, $"109: {nameof(AudioComponent)}.{nameof(MaterializeFrame)}()");
ffmpeg.swr_init(Scaler);
LastSourceSpec = sourceSpec;
}
// Allocate the unmanaged output buffer
if (target.AudioBufferLength != targetSpec.BufferLength)
{
if (target.AudioBuffer != IntPtr.Zero)
{
Marshal.FreeHGlobal(target.AudioBuffer);
}
target.AudioBufferLength = targetSpec.BufferLength;
target.AudioBuffer = Marshal.AllocHGlobal(targetSpec.BufferLength);
}
var outputBufferPtr = (byte *)target.AudioBuffer;
// Execute the conversion (audio scaling). It will return the number of samples that were output
var outputSamplesPerChannel =
ffmpeg.swr_convert(
Scaler,
&outputBufferPtr,
targetSpec.SamplesPerChannel,
source.Pointer->extended_data,
source.Pointer->nb_samples);
// Compute the buffer length
var outputBufferLength =
ffmpeg.av_samples_get_buffer_size(null, targetSpec.ChannelCount, outputSamplesPerChannel, targetSpec.Format, 1);
// Flag the block if we have to
target.IsStartTimeGuessed = source.HasValidStartTime == false;
// Try to fix the start time, duration and End time if we don't have valid data
if (source.HasValidStartTime == false && siblings != null && siblings.Count > 0)
{
// Get timing information from the last sibling
var lastSibling = siblings[siblings.Count - 1];
// We set the target properties
target.StartTime = lastSibling.EndTime;
target.Duration = source.Duration.Ticks > 0 ? source.Duration : lastSibling.Duration;
target.EndTime = TimeSpan.FromTicks(target.StartTime.Ticks + target.Duration.Ticks);
}
else
{
// We set the target properties directly from the source
target.StartTime = source.StartTime;
target.Duration = source.Duration;
target.EndTime = source.EndTime;
}
target.BufferLength = outputBufferLength;
target.ChannelCount = targetSpec.ChannelCount;
target.SampleRate = targetSpec.SampleRate;
target.SamplesPerChannel = outputSamplesPerChannel;
target.StreamIndex = input.StreamIndex;
return(target);
}
