private static IMFAttributes CreateAudioAttributes(AudioFormat audioOutput)
{
uint codecConfig = 0;
object supportedAttributes = null;
// Create the audio attributes
IMFAttributes audioAttributes = null;
// Generate the audio media type
uint elementsNumber = 0;
uint selectedType = 0;
int avgBitrateDiff = int.MaxValue;
uint avgBytePerSecond = uint.MaxValue;
// Get the available audio ouput types for the required sub type
IMFCollection availableTypes = null;
MFHelper.MFTranscodeGetAudioOutputAvailableTypes(audioOutput.Subtype, (uint)Enums.MFT_ENUM_FLAG.MFT_ENUM_FLAG_ALL, codecConfig, out availableTypes);
// Get the number of types
availableTypes.GetElementCount(out elementsNumber);
// Find the best match for our needs
for (uint elementIndex = 0; elementIndex < elementsNumber; elementIndex++)
{
// Get the next element
availableTypes.GetElement(elementIndex, out supportedAttributes);
audioAttributes = (IMFAttributes)supportedAttributes;
// Get the byte per second
audioAttributes.GetUINT32(new Guid(Consts.MF_MT_AUDIO_AVG_BYTES_PER_SECOND), out avgBytePerSecond);
// If this is better than the last one found remember the index
if (Math.Abs((int)avgBytePerSecond - (int)audioOutput.AvgBytePerSecond) < avgBitrateDiff)
{
selectedType = elementIndex;
avgBitrateDiff = Math.Abs((int)avgBytePerSecond - (int)audioOutput.AvgBytePerSecond);
}
audioAttributes = null;
}
// Get the best audio type found
availableTypes.GetElement(selectedType, out supportedAttributes);
audioAttributes = (IMFAttributes)supportedAttributes;
return(audioAttributes);
}
private IMFMediaType CreateTargetAudioMediaType()
{
IMFMediaType mediaType = null;
if (audioOutput.Subtype.Equals(new Guid(Consts.MFAudioFormat_AAC)))
{
// Create the AAC media type
MFHelper.MFCreateMediaType(out mediaType);
mediaType.SetGUID(new Guid(Consts.MF_MT_MAJOR_TYPE), new Guid(Consts.MFMediaType_Audio));
mediaType.SetGUID(new Guid(Consts.MF_MT_SUBTYPE), this.audioOutput.Subtype);
mediaType.SetUINT32(new Guid(Consts.MF_MT_AUDIO_AVG_BYTES_PER_SECOND), this.audioOutput.AvgBytePerSecond);
mediaType.SetUINT32(new Guid(Consts.MF_MT_AUDIO_NUM_CHANNELS), this.audioOutput.NumOfChannels);
mediaType.SetUINT32(new Guid(Consts.MF_MT_AUDIO_SAMPLES_PER_SECOND), this.audioOutput.SamplesPerSecond);
mediaType.SetUINT32(new Guid(Consts.MF_MT_AUDIO_BLOCK_ALIGNMENT), this.audioOutput.BlockAlignment);
mediaType.SetUINT32(new Guid(Consts.MF_MT_AUDIO_BITS_PER_SAMPLE), this.audioOutput.BitsPerSample);
}
else
{
// Create the WMA media type
uint codecConfig = 0;
uint elementsNumber = 0;
uint selectedType = 0;
int avgBitrateDiff = int.MaxValue;
uint avgBytePerSecond = uint.MaxValue;
object supportedAttributes = null;
// Get the available audio ouput types for the required sub type
IMFCollection availableTypes = null;
MFHelper.MFTranscodeGetAudioOutputAvailableTypes(audioOutput.Subtype, (uint)Enums.MFT_ENUM_FLAG.MFT_ENUM_FLAG_ALL, codecConfig, out availableTypes);
// Get the number of types
availableTypes.GetElementCount(out elementsNumber);
for (uint elementIndex = 0; elementIndex < elementsNumber; elementIndex++)
{
// Get the next element
availableTypes.GetElement(elementIndex, out supportedAttributes);
mediaType = (IMFMediaType)supportedAttributes;
// Get the byte per second
mediaType.GetUINT32(new Guid(Consts.MF_MT_AUDIO_AVG_BYTES_PER_SECOND), out avgBytePerSecond);
// If this is better than the last one found remember the index
if (Math.Abs((int)avgBytePerSecond - (int)audioOutput.AvgBytePerSecond) < avgBitrateDiff)
{
selectedType = elementIndex;
avgBitrateDiff = Math.Abs((int)avgBytePerSecond - (int)audioOutput.AvgBytePerSecond);
}
mediaType = null;
}
// Get the best audio type found
availableTypes.GetElement(selectedType, out supportedAttributes);
mediaType = (IMFMediaType)supportedAttributes;
}
return(mediaType);
}