/// <summary>
/// Decodes a stream of Ogg Vorbis data into wav file format.
/// </summary>
/// <returns>
/// A MemoryStream with the entire decoded stream.
/// </returns>
/// <param name='input'>
/// Ogg Vorbis data to be decoded
/// </param>
/// <param name='output'>
/// <para>Stream to write wav data.</para>
/// <para>If writeWavHeader is true then this stream must be seekable.</para>
/// </param>
/// <param name='writeWavHeader'>
/// Write wav header in the beginning of the returned stream.
/// </param>
public static void DecodeStream(Stream input, Stream output, bool writeWavHeader)
{
int convsize = 4096 * 2;
byte[] convbuffer = new byte[convsize]; // take 8k out of the data segment, not the stack
long start = output.Position;
DebugWriter s_err = new DebugWriter();
if (writeWavHeader && !output.CanSeek)
throw new ArgumentException("To write wav header, the output stream must be seekable.", "output");
if (writeWavHeader)
output.Seek(HEADER_SIZE, SeekOrigin.Current); // reserve place for WAV header
SyncState oy = new SyncState(); // sync and verify incoming physical bitstream
StreamState os = new StreamState(); // take physical pages, weld into a logical stream of packets
Page og = new Page(); // one Ogg bitstream page. Vorbis packets are inside
Packet op = new Packet(); // one raw packet of data for decode
Info vi = new Info(); // struct that stores all the static vorbis bitstream settings
Comment vc = new Comment(); // struct that stores all the bitstream user comments
DspState vd = new DspState(); // central working state for the packet->PCM decoder
Block vb = new Block(vd); // local working space for packet->PCM decode
int bytes = 0;
// Decode setup
oy.init(); // Now we can read pages
// we repeat if the bitstream is chained
while (true)
{
int eos = 0;
// 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 = oy.buffer(4096);
bytes = input.Read(oy.data, index, 4096);
oy.wrote(bytes);
// Get the first page.
if (oy.pageout(og) != 1)
{
// have we simply run out of data? If so, we're done.
if (bytes < 4096)
break;
// error case. Must not be Vorbis data
s_err.WriteLine("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
os.init(og.serialno());
// 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.
vi.init();
vc.init();
if (os.pagein(og) < 0)
{
// error; stream version mismatch perhaps
s_err.WriteLine("Error reading first page of Ogg bitstream data.");
}
if (os.packetout(op) != 1)
{
// no page? must not be vorbis
s_err.WriteLine("Error reading initial header packet.");
}
if (vi.synthesis_headerin(vc, op) < 0)
{
// error case; not a vorbis header
s_err.WriteLine("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 = oy.pageout(og);
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)
{
os.pagein(og); // we can ignore any errors here
// as they'll also become apparent
// at packetout
while (i < 2)
{
result = os.packetout(op);
if (result == 0)
break;
if (result == -1)
{
// Uh oh; data at some point was corrupted or missing!
// We can't tolerate that in a header. Die.
s_err.WriteLine("Corrupt secondary header. Exiting.");
}
vi.synthesis_headerin(vc, op);
i++;
}
}
}
// no harm in not checking before adding more
index = oy.buffer(4096);
bytes = input.Read(oy.data, index, 4096);
if (bytes == 0 && i < 2)
{
s_err.WriteLine("End of file before finding all Vorbis headers!");
}
oy.wrote(bytes);
}
// Throw the comments plus a few lines about the bitstream we're
// decoding
{
byte[][] ptr = vc.user_comments;
for (int j = 0; j < vc.user_comments.Length; j++)
{
if (ptr [j] == null)
break;
s_err.WriteLine(vc.getComment(j));
}
s_err.WriteLine("\nBitstream is " + vi.channels + " channel, " + vi.rate + "Hz");
s_err.WriteLine("Encoded by: " + vc.getVendor() + "\n");
}
convsize = 4096 / vi.channels;
// OK, got and parsed all three headers. Initialize the Vorbis
// packet->PCM decoder.
vd.synthesis_init(vi); // central decode state
vb.init(vd); // 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[vi.channels];
// The rest is just a straight decode loop until end of stream
while (eos == 0)
{
while (eos == 0)
{
int result = oy.pageout(og);
if (result == 0)
break; // need more data
if (result == -1)
{
// missing or corrupt data at this page position
s_err.WriteLine("Corrupt or missing data in bitstream; continuing...");
} else
{
os.pagein(og); // can safely ignore errors at
// this point
while (true)
{
result = os.packetout(op);
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 (vb.synthesis(op) == 0)
{ // test for success!
vd.synthesis_blockin(vb);
}
// **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 = vd.synthesis_pcmout(_pcm, _index)) > 0)
{
float[][] pcm = _pcm [0];
bool clipflag = false;
int bout = (samples < convsize ? samples : convsize);
// convert floats to 16 bit signed ints (host order) and
// interleave
for (i = 0; i < vi.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;
clipflag = true;
}
if (val < -32768)
{
val = -32768;
clipflag = true;
}
if (val < 0)
val = val | 0x8000;
convbuffer [ptr] = (byte)(val);
convbuffer [ptr + 1] = (byte)((uint)val >> 8);
ptr += 2 * (vi.channels);
}
}
if (clipflag)
{
//s_err.WriteLine("Clipping in frame "+vd.sequence);
}
output.Write(convbuffer, 0, 2 * vi.channels * bout);
vd.synthesis_read(bout); // tell libvorbis how
// many samples we
// actually consumed
}
}
}
if (og.eos() != 0)
eos = 1;
}
}
if (eos == 0)
{
index = oy.buffer(4096);
bytes = input.Read(oy.data, index, 4096);
oy.wrote(bytes);
if (bytes == 0)
eos = 1;
}
}
// clean up this logical bitstream; before exit we see if we're
// followed by another [chained]
os.clear();
// ogg_page and ogg_packet structs always point to storage in
// libvorbis. They're never freed or manipulated directly
vb.clear();
vd.clear();
vi.clear(); // must be called last
}
// OK, clean up the framer
oy.clear();
s_err.WriteLine("Done.");
if (writeWavHeader)
{
long end = output.Position;
int length = (int)(end - (start + HEADER_SIZE));
output.Seek(start, SeekOrigin.Begin);
WriteHeader(output, length, vi.rate, (ushort)16, (ushort)vi.channels);
output.Seek(end, SeekOrigin.Begin);
}
}
