org.xiph.speex.spi

Class Speex2PcmAudioInputStream


public class Speex2PcmAudioInputStream
extends FilteredAudioInputStream

Converts an Ogg Speex bitstream into a PCM 16bits/sample audio stream.
Version:
$Revision: 1.5 $
Author:
Marc Gimpel, Wimba S.A. (mgimpel@horizonwimba.com)

Field Summary

private Bits
bits
Speex bit packing and unpacking class.
private int
channelCount
The number of audio channels (1=mono, 2=stereo).
private float[]
decodedData
Array containing the decoded audio samples.
private Decoder
decoder
Speex Decoder.
private int
frameSize
The frame size, in samples.
private int
framesPerPacket
The number of Speex frames that will be put in each Ogg packet.
private boolean
initialised
Flag to indicate if this Stream has been initialised.
private byte[]
outputData
Array containing the decoded audio samples converted into bytes.
private int
packetCount
The number of Ogg packets that have been decoded in the current page.
private byte[]
packetSizes
Array containing the sizes of Ogg packets in the current page.
private int
packetsPerOggPage
The number of Ogg packets that are in each Ogg page.
private int
sampleRate
The sample rate of the audio, in samples per seconds (Hz).
private int
streamSerialNumber
A unique serial number that identifies the Ogg stream.

Fields inherited from class org.xiph.speex.spi.FilteredAudioInputStream

DEFAULT_BUFFER_SIZE, buf, count, in, marklimit, markpos, pos, prebuf, precount, prepos, single

Constructor Summary

Speex2PcmAudioInputStream(InputStream in, AudioFormat format, long length)
Constructor
Speex2PcmAudioInputStream(InputStream in, AudioFormat format, long length, int size)
Constructor

Method Summary

int
available()
Returns the number of bytes that can be read from this inputstream without blocking.
protected void
decode(byte[] data, int offset, int len)
This is where the actual decoding takes place.
protected void
fill()
Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks.
protected void
initialise(boolean blocking)
Initialises the Ogg Speex to PCM InputStream.
private static int
readInt(byte[] data, int offset)
Converts Little Endian (Windows) bytes to an int (Java uses Big Endian).
private void
readOggPageHeader()
Read the Ogg Page header and extract the speex packet sizes.
long
skip(long n)
See the general contract of the skip method of InputStream.

Methods inherited from class org.xiph.speex.spi.FilteredAudioInputStream

available, checkIfStillOpen, close, fill, makeSpace, mark, markSupported, read, read, reset, skip

Field Details

bits

private Bits bits
Speex bit packing and unpacking class.

channelCount

private int channelCount
The number of audio channels (1=mono, 2=stereo).

decodedData

private float[] decodedData
Array containing the decoded audio samples.

decoder

private Decoder decoder
Speex Decoder.

frameSize

private int frameSize
The frame size, in samples.

framesPerPacket

private int framesPerPacket
The number of Speex frames that will be put in each Ogg packet.

initialised

private boolean initialised
Flag to indicate if this Stream has been initialised.

outputData

private byte[] outputData
Array containing the decoded audio samples converted into bytes.

packetCount

private int packetCount
The number of Ogg packets that have been decoded in the current page.

packetSizes

private byte[] packetSizes
Array containing the sizes of Ogg packets in the current page.

packetsPerOggPage

private int packetsPerOggPage
The number of Ogg packets that are in each Ogg page.

sampleRate

private int sampleRate
The sample rate of the audio, in samples per seconds (Hz).

streamSerialNumber

private int streamSerialNumber
A unique serial number that identifies the Ogg stream.

Constructor Details

Speex2PcmAudioInputStream

public Speex2PcmAudioInputStream(InputStream in,
                                 AudioFormat format,
                                 long length)
Constructor
Parameters:
in - the underlying input stream.
format - the target format of this stream's audio data.
length - the length in sample frames of the data in this stream.

Speex2PcmAudioInputStream

public Speex2PcmAudioInputStream(InputStream in,
                                 AudioFormat format,
                                 long length,
                                 int size)
Constructor
Parameters:
in - the underlying input stream.
format - the target format of this stream's audio data.
length - the length in sample frames of the data in this stream.
size - the buffer size.

Method Details

available

public int available()
            throws IOException
Returns the number of bytes that can be read from this inputstream without blocking.

The available method of FilteredAudioInputStream returns the sum of the the number of bytes remaining to be read in the buffer (count - pos). The result of calling the available method of the underlying inputstream is not used, as this data will have to be filtered, and thus may not be the same size after processing (although subclasses that do the filtering should override this method and use the amount of data available in the underlying inputstream).

Overrides:
available in interface FilteredAudioInputStream
Returns:
the number of bytes that can be read from this inputstream without blocking.

decode

protected void decode(byte[] data,
                      int offset,
                      int len)
            throws StreamCorruptedException
This is where the actual decoding takes place.
Parameters:
data - the array of data to decode.
offset - the offset from which to start reading the data.
len - the length of data to read from the array.

fill

protected void fill()
            throws IOException
Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks. Assumes that it is being called by a synchronized method. This method also assumes that all data has already been read in, hence pos > count.
Overrides:
fill in interface FilteredAudioInputStream

initialise

protected void initialise(boolean blocking)
            throws IOException
Initialises the Ogg Speex to PCM InputStream. Read the Ogg Speex header and extract the speex decoder parameters to initialise the decoder. Then read the Comment header. Ogg Header description:
  0 -  3: capture_pattern
       4: stream_structure_version
       5: header_type_flag (2=bos: beginning of sream)
  6 - 13: absolute granule position
 14 - 17: stream serial number
 18 - 21: page sequence no
 22 - 25: page checksum
      26: page_segments
 27 -...: segment_table
 
Speex Header description
  0 -  7: speex_string
  8 - 27: speex_version
 28 - 31: speex_version_id
 32 - 35: header_size
 36 - 39: rate
 40 - 43: mode (0=narrowband, 1=wb, 2=uwb)
 44 - 47: mode_bitstream_version
 48 - 51: nb_channels
 52 - 55: bitrate
 56 - 59: frame_size
 60 - 63: vbr
 64 - 67: frames_per_packet
 68 - 71: extra_headers
 72 - 75: reserved1
 76 - 79: reserved2
 
Parameters:
blocking - whether the method should block until initialisation is successfully completed or not.

readInt

private static int readInt(byte[] data,
                           int offset)
Converts Little Endian (Windows) bytes to an int (Java uses Big Endian).
Parameters:
data - the data to read.
offset - the offset from which to start reading.
Returns:
the integer value of the reassembled bytes.

readOggPageHeader

private void readOggPageHeader()
            throws IOException
Read the Ogg Page header and extract the speex packet sizes. Note: the checksum is ignores. Note: the method should no block on a read because it will not read more then is available

skip

public long skip(long n)
            throws IOException
See the general contract of the skip method of InputStream.
Overrides:
skip in interface FilteredAudioInputStream
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.

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