public async Task <ServerAudioInfo> GrabFrameInfoAsync(ShoutcastStreamProcessor processor, ServerAudioInfo serverSentInfo)
{
ServerAudioInfo audioInfo = new ServerAudioInfo();
audioInfo.AudioFormat = StreamAudioFormat.AAC_ADTS;
//load the first byte
byte lastByte = await processor.ReadByteFromSocketAsync();
while (true) //wait for frame sync
{
var curByte = await processor.ReadByteFromSocketAsync();
if (AAC_ADTSParser.IsFrameSync(lastByte, curByte)) //check if we're at the frame sync. if we are, parse some of the audio data
{
byte[] header = new byte[AAC_ADTSParser.HeaderLength];
header[0] = lastByte;
header[1] = curByte;
Array.Copy(await processor.ReadBytesFromSocketAsync(5), 0, header, 2, 5);
//todo deal with CRC
try
{
audioInfo.SampleRate = (uint)AAC_ADTSParser.GetSampleRate(header);
audioInfo.ChannelCount = (uint)AAC_ADTSParser.GetChannelCount(header);
//bitrate gets sent by the server.
audioInfo.BitRate = serverSentInfo.BitRate;
//audioInfo.BitRate = (uint)AAC_ADTSParser.GetBitRate(header);
//if (audioInfo.BitRate == 0) throw new Exception("Unknown bitrate.");
}
catch (IndexOutOfRangeException)
{
//probably not the header. continue.
lastByte = curByte;
continue;
}
break;
}
else
{
lastByte = curByte;
}
}
return(audioInfo);
}
private async Task <AudioEncodingProperties> ParseEncodingFromMediaAsync()
{
//grab the first frame and strip it for information
AudioEncodingProperties obtainedProperties = null;
IBuffer buffer = null;
switch (AudioInfo.AudioFormat)
{
case StreamAudioFormat.MP3:
{
//load the first byte
await socketReader.LoadAsync(1);
byte lastByte = socketReader.ReadByte();
byteOffset += 1;
metadataPos += 1;
while (true) //wait for frame sync
{
await socketReader.LoadAsync(1);
var curByte = socketReader.ReadByte();
if (MP3Parser.IsFrameSync(lastByte, curByte)) //check if we're at the frame sync. if we are, parse some of the audio data
{
byteOffset += 1;
metadataPos += 1;
byte[] header = new byte[MP3Parser.HeaderLength];
header[0] = lastByte;
header[1] = curByte;
await socketReader.LoadAsync(2);
header[2] = socketReader.ReadByte();
header[3] = socketReader.ReadByte();
byteOffset += 2;
metadataPos += 2;
AudioInfo.SampleRate = (uint)MP3Parser.GetSampleRate(header);
AudioInfo.ChannelCount = (uint)MP3Parser.GetChannelCount(header);
AudioInfo.BitRate = (uint)MP3Parser.GetBitRate(header);
if (AudioInfo.BitRate == 0)
{
throw new Exception("Unknown bitrate.");
}
break;
}
else
{
byteOffset += 1;
metadataPos += 1;
lastByte = curByte;
}
}
//skip the entire first frame/sample to get back on track
await socketReader.LoadAsync(mp3_sampleSize - MP3Parser.HeaderLength);
buffer = socketReader.ReadBuffer(mp3_sampleSize - MP3Parser.HeaderLength);
byteOffset += mp3_sampleSize - MP3Parser.HeaderLength;
obtainedProperties = AudioEncodingProperties.CreateMp3((uint)AudioInfo.SampleRate, (uint)AudioInfo.ChannelCount, AudioInfo.BitRate);
break;
}
case StreamAudioFormat.AAC:
{
//obtainedProperties = AudioEncodingProperties.CreateAac(0, 2, 0);
throw new Exception("Not supported.");
}
case StreamAudioFormat.AAC_ADTS:
{
//load the first byte
await socketReader.LoadAsync(1);
byte lastByte = socketReader.ReadByte();
byteOffset += 1;
metadataPos += 1;
while (true) //wait for frame sync
{
await socketReader.LoadAsync(1);
var curByte = socketReader.ReadByte();
if (AAC_ADTSParser.IsFrameSync(lastByte, curByte)) //check if we're at the frame sync. if we are, parse some of the audio data
{
byteOffset += 1;
metadataPos += 1;
byte[] header = new byte[AAC_ADTSParser.HeaderLength];
header[0] = lastByte;
header[1] = curByte;
await socketReader.LoadAsync(5);
header[2] = socketReader.ReadByte();
header[3] = socketReader.ReadByte();
header[4] = socketReader.ReadByte();
header[5] = socketReader.ReadByte();
header[6] = socketReader.ReadByte();
byteOffset += 5;
metadataPos += 5;
//todo deal with CRC
AudioInfo.SampleRate = (uint)AAC_ADTSParser.GetSampleRate(header);
AudioInfo.ChannelCount = (uint)AAC_ADTSParser.GetChannelCount(header);
//bitrate gets sent by the server.
//bitRate = (uint)AAC_ADTSParser.GetBitRate(header);
if (AudioInfo.BitRate == 0)
{
throw new Exception("Unknown bitrate.");
}
//skip the entire first frame/sample to get back on track
await socketReader.LoadAsync(aac_adts_sampleSize - AAC_ADTSParser.HeaderLength);
buffer = socketReader.ReadBuffer(aac_adts_sampleSize - AAC_ADTSParser.HeaderLength);
byteOffset += aac_adts_sampleSize - AAC_ADTSParser.HeaderLength;
obtainedProperties = AudioEncodingProperties.CreateAacAdts((uint)AudioInfo.SampleRate, (uint)AudioInfo.ChannelCount, AudioInfo.BitRate);
break;
}
else
{
byteOffset += 1;
metadataPos += 1;
lastByte = curByte;
}
}
}
break;
default:
break;
}
metadataPos += buffer.Length; //very important or it will throw everything off!
return(obtainedProperties);
}
