private IEnumerable <ArraySegment <byte> > DecodeTo(Stream OggBaseStream, InfoHolderClass InfoHolder)
{
byte[] buffer;
int bytes = 0;
int convsize = 4096 * 2;
var convbuffer = new byte[convsize]; // take 8k out of the data segment, not the stack
var SyncState = new SyncState(); // sync and verify incoming physical bitstream
var StreamState = new StreamState(); // take physical pages, weld into a logical stream of packets
var Page = new Page(); // one Ogg bitstream page. Vorbis packets are inside
var Packet = new Packet(); // one raw packet of data for decode
var Info = new Info(); // struct that stores all the static vorbis bitstream settings
var Comment = new Comment(); // struct that stores all the bitstream user comments
var DspState = new DspState(); // central working state for the packet->PCM decoder
var Block = new Block(DspState); // local working space for packet->PCM decode
// Decode setup
SyncState.Init(); // Now we can read pages
// we repeat if the bitstream is chained
while (true)
{
bool eos = false;
// grab some data at the head of the stream. We want the first page
// (which is guaranteed to be small and only contain the Vorbis
// stream initial header) We need the first page to get the stream
// serialno.
// submit a 4k block to libvorbis' Ogg layer
int index = SyncState.Buffer(4096);
buffer = SyncState.Data;
bytes = OggBaseStream.Read(buffer, index, 4096);
SyncState.Wrote(bytes);
// Get the first page.
int _result = SyncState.PageOut(Page);
if (_result != 1)
{
// have we simply run out of data? If so, we're done.
if (bytes < 4096)
{
break;
}
Debug.WriteLine(bytes + "; " + _result);
//File.WriteAllBytes();
// error case. Must not be Vorbis data
//Debug.WriteLine("Input does not appear to be an Ogg bitstream.");
throw (new Exception("Input does not appear to be an Ogg bitstream."));
}
// Get the serial number and set up the rest of decode.
// serialno first; use it to set up a logical stream
StreamState.Init(Page.BitStreamSerialNumber);
// extract the initial header from the first page and verify that the
// Ogg bitstream is in fact Vorbis data
// I handle the initial header first instead of just having the code
// read all three Vorbis headers at once because reading the initial
// header is an easy way to identify a Vorbis bitstream and it's
// useful to see that functionality seperated out.
Info.Init();
Comment.init();
// error; stream version mismatch perhaps
if (StreamState.PageIn(Page) < 0)
{
throw (new Exception("Error reading first page of Ogg bitstream data."));
}
// no page? must not be vorbis
if (StreamState.PacketOut(Packet) != 1)
{
throw (new Exception("Error reading initial header packet."));
}
// error case; not a vorbis header
if (Info.SynthesisHeaderIn(Comment, Packet) < 0)
{
throw (new Exception("This Ogg bitstream does not contain Vorbis audio data."));
}
// At this point, we're sure we're Vorbis. We've set up the logical
// (Ogg) bitstream decoder. Get the comment and codebook headers and
// set up the Vorbis decoder
// The next two packets in order are the comment and codebook headers.
// They're likely large and may span multiple pages. Thus we reead
// and submit data until we get our two pacakets, watching that no
// pages are missing. If a page is missing, error out; losing a
// header page is the only place where missing data is fatal. */
int i = 0;
while (i < 2)
{
while (i < 2)
{
int result = SyncState.PageOut(Page);
if (result == 0)
{
break; // Need more data
}
// Don't complain about missing or corrupt data yet. We'll
// catch it at the packet output phase
if (result == 1)
{
StreamState.PageIn(Page); // we can ignore any errors here
// as they'll also become apparent
// at packetout
while (i < 2)
{
result = StreamState.PacketOut(Packet);
if (result == 0)
{
break;
}
// Uh oh; data at some point was corrupted or missing!
// We can't tolerate that in a header. Die.
if (result == -1)
{
throw (new Exception("Corrupt secondary header. Exiting."));
}
Info.SynthesisHeaderIn(Comment, Packet);
i++;
}
}
}
// no harm in not checking before adding more
index = SyncState.Buffer(4096);
buffer = SyncState.Data;
bytes = OggBaseStream.Read(buffer, index, 4096);
if (bytes == 0 && i < 2)
{
throw (new Exception("End of file before finding all Vorbis headers!"));
}
SyncState.Wrote(bytes);
}
// Throw the comments plus a few lines about the bitstream we're
// decoding
#if false
{
byte[][] ptr = Comment.user_comments;
for (int j = 0; j < ptr.Length; j++)
{
if (ptr[j] == null)
{
break;
}
Debug.WriteLine(Util.InternalEncoding.GetString(ptr[j], 0, ptr[j].Length - 1));
}
Debug.WriteLine("\nBitstream is {0} channel, {1}Hz", Info.channels, Info.rate);
Debug.WriteLine("Encoded by: {0}\n", Util.InternalEncoding.GetString(Comment.vendor, 0, Comment.vendor.Length - 1));
}
#endif
convsize = 4096 / Info.Channels;
//convsize = 4096 / Info.channels * 2;
InfoHolder.Info = Info;
yield return(new ArraySegment <byte>());
// OK, got and parsed all three headers. Initialize the Vorbis
// packet->PCM decoder.
DspState.synthesis_init(Info); // central decode state
Block.init(DspState); // local state for most of the decode
// so multiple block decodes can
// proceed in parallel. We could init
// multiple vorbis_block structures
// for vd here
float[][][] _pcm = new float[1][][];
int[] _index = new int[Info.Channels];
// The rest is just a straight decode loop until end of stream
while (!eos)
{
while (!eos)
{
int result = SyncState.PageOut(Page);
if (result == 0)
{
break; // need more data
}
if (result == -1)
{
// missing or corrupt data at this page position
Debug.WriteLine("Corrupt or missing data in bitstream; continuing...");
}
else
{
StreamState.PageIn(Page); // can safely ignore errors at
// this point
while (true)
{
result = StreamState.PacketOut(Packet);
if (result == 0)
{
break; // need more data
}
if (result == -1)
{ // missing or corrupt data at this page position
// no reason to complain; already complained above
}
else
{
// we have a packet. Decode it
int samples;
if (Block.synthesis(Packet) == 0)
{ // test for success!
DspState.synthesis_blockin(Block);
}
// **pcm is a multichannel float vector. In stereo, for
// example, pcm[0] is left, and pcm[1] is right. samples is
// the size of each channel. Convert the float values
// (-1.<=range<=1.) to whatever PCM format and write it out
while ((samples = DspState.synthesis_pcmout(_pcm, _index)) > 0)
{
float[][] pcm = _pcm[0];
int bout = (samples < convsize ? samples : convsize);
// convert floats to 16 bit signed ints (host order) and
// interleave
for (i = 0; i < Info.Channels; i++)
{
int ptr = i * 2;
//int ptr=i;
int mono = _index[i];
for (int j = 0; j < bout; j++)
{
int val = (int)(pcm[i][mono + j] * 32767.0);
// short val=(short)(pcm[i][mono+j]*32767.);
// int val=(int)Math.round(pcm[i][mono+j]*32767.);
// might as well guard against clipping
if (val > 32767)
{
val = 32767;
}
if (val < -32768)
{
val = -32768;
}
if (val < 0)
{
val = val | 0x8000;
}
convbuffer[ptr] = (byte)(val);
convbuffer[ptr + 1] = (byte)(((uint)val) >> 8);
ptr += 2 * (Info.Channels);
}
}
// System.out.write(convbuffer, 0, 2*vi.channels*bout);
//throw(new NotImplementedException("ccccccccc"));
//OutputBuffer.Write(convbuffer, 0, 2 * Info.channels * bout);
InfoHolder.BufferLength = 2 * Info.Channels * convsize;
yield return(new ArraySegment <byte>(convbuffer, 0, 2 * Info.Channels * bout));
// tell libvorbis how
// many samples we
// actually consumed
DspState.synthesis_read(bout);
}
}
}
if (Page.EndOfStream)
{
eos = true;
}
}
}
if (!eos)
{
index = SyncState.Buffer(4096);
buffer = SyncState.Data;
bytes = OggBaseStream.Read(buffer, index, 4096);
SyncState.Wrote(bytes);
if (bytes == 0)
{
eos = true;
}
}
}
// clean up this logical bitstream; before exit we see if we're
// followed by another [chained]
StreamState.Clear();
// ogg_page and ogg_packet structs always point to storage in
// libvorbis. They're never freed or manipulated directly
Block.clear();
DspState.clear();
Info.Clear(); // must be called last
yield return(new ArraySegment <byte>());
}
// OK, clean up the framer
SyncState.Clear();
}