/// <summary>
/// Creates a source audio spec based on the info in the given audio frame
/// </summary>
/// <param name="frame">The frame.</param>
/// <returns>The audio parameters</returns>
internal static FFAudioParams CreateSource(AVFrame *frame)
{
var spec = new FFAudioParams(frame);
if (spec.ChannelLayout == 0)
{
spec.ChannelLayout = ffmpeg.av_get_default_channel_layout(spec.ChannelCount);
}
return(spec);
}
/// <summary>
/// Initializes static members of the <see cref="FFAudioParams"/> class.
/// </summary>
static FFAudioParams()
{
Output = new FFAudioParams()
{
ChannelCount = Constants.Audio.ChannelCount,
SampleRate = Constants.Audio.SampleRate,
Format = Constants.Audio.SampleFormat
};
Output.ChannelLayout = ffmpeg.av_get_default_channel_layout(Output.ChannelCount);
Output.SamplesPerChannel = Output.SampleRate;
Output.BufferLength = ffmpeg.av_samples_get_buffer_size(
null, Output.ChannelCount, Output.SamplesPerChannel + Constants.Audio.BufferPadding, Output.Format, 1);
}
/// <summary>
/// Creates a target audio spec using the sample quantities provided
/// by the given source audio frame
/// </summary>
/// <param name="frame">The frame.</param>
/// <returns>The audio parameters</returns>
internal static FFAudioParams CreateTarget(AVFrame *frame)
{
var spec = new FFAudioParams
{
ChannelCount = Output.ChannelCount,
Format = Output.Format,
SampleRate = Output.SampleRate,
ChannelLayout = Output.ChannelLayout
};
// The target transform is just a ratio of the source frame's sample. This is how many samples we desire
spec.SamplesPerChannel = Convert.ToInt32(Convert.ToDouble(frame->nb_samples) * spec.SampleRate / frame->sample_rate);
spec.BufferLength = ffmpeg.av_samples_get_buffer_size(
null, spec.ChannelCount, spec.SamplesPerChannel + Constants.Audio.BufferPadding, spec.Format, 1);
return(spec);
}
/// <summary>
/// Determines if the audio specs are compatible between them.
/// They must share format, channel count, layout and sample rate
/// </summary>
/// <param name="a">a.</param>
/// <param name="b">The b.</param>
/// <returns>True if the params are compatible, false otherwise.</returns>
internal static bool AreCompatible(FFAudioParams a, FFAudioParams b)
{
if (a.Format != b.Format)
{
return(false);
}
if (a.ChannelCount != b.ChannelCount)
{
return(false);
}
if (a.ChannelLayout != b.ChannelLayout)
{
return(false);
}
return(a.SampleRate == b.SampleRate);
}