-class LayerIDecoder implements FrameDecoder
-{
- protected Bitstream stream;
- protected Header header;
- protected SynthesisFilter filter1, filter2;
- protected Obuffer buffer;
- protected int which_channels;
- protected int mode;
-
- protected int num_subbands;
- protected Subband[] subbands;
- protected Crc16 crc = null; // new Crc16[1] to enable CRC checking.
-
- public LayerIDecoder()
- {
- crc = new Crc16();
- }
-
- public void create(Bitstream stream0, Header header0,
- SynthesisFilter filtera, SynthesisFilter filterb,
- Obuffer buffer0, int which_ch0)
- {
- stream = stream0;
- header = header0;
- filter1 = filtera;
- filter2 = filterb;
- buffer = buffer0;
- which_channels = which_ch0;
-
- }
-
- public void decodeFrame() throws DecoderException
- {
-
- num_subbands = header.number_of_subbands();
- subbands = new Subband[32];
- mode = header.mode();
-
- createSubbands();
-
- readAllocation();
- readScaleFactorSelection();
-
- if ((crc != null) || header.checksum_ok())
- {
- readScaleFactors();
-
- readSampleData();
- }
-
- }
-
- protected void createSubbands()
- {
- int i;
- if (mode == Header.SINGLE_CHANNEL)
- for (i = 0; i < num_subbands; ++i)
- subbands[i] = new SubbandLayer1(i);
- else if (mode == Header.JOINT_STEREO)
- {
- for (i = 0; i < header.intensity_stereo_bound(); ++i)
- subbands[i] = new SubbandLayer1Stereo(i);
- for (; i < num_subbands; ++i)
- subbands[i] = new SubbandLayer1IntensityStereo(i);
- }
- else
- {
- for (i = 0; i < num_subbands; ++i)
- subbands[i] = new SubbandLayer1Stereo(i);
- }
- }
-
- protected void readAllocation() throws DecoderException
- {
- // start to read audio data:
- for (int i = 0; i < num_subbands; ++i)
- subbands[i].read_allocation(stream, header, crc);
-
- }
-
- protected void readScaleFactorSelection()
- {
- // scale factor selection not present for layer I.
- }
-
- protected void readScaleFactors()
- {
- for (int i = 0; i < num_subbands; ++i)
- subbands[i].read_scalefactor(stream, header);
- }
-
- protected void readSampleData()
- {
- boolean read_ready = false;
- boolean write_ready = false;
- int mode = header.mode();
- int i;
- do
- {
- for (i = 0; i < num_subbands; ++i)
- read_ready = subbands[i].read_sampledata(stream);
- do
- {
- for (i = 0; i < num_subbands; ++i)
- write_ready = subbands[i].put_next_sample(which_channels,filter1, filter2);
-
- filter1.calculate_pcm_samples(buffer);
- if ((which_channels == OutputChannels.BOTH_CHANNELS) && (mode != Header.SINGLE_CHANNEL))
- filter2.calculate_pcm_samples(buffer);
- } while (!write_ready);
- } while (!read_ready);
-
- }
-
- /**
- * Abstract base class for subband classes of layer I and II
- */
- static abstract class Subband
- {
- /*
- * Changes from version 1.1 to 1.2:
- * - array size increased by one, although a scalefactor with index 63
- * is illegal (to prevent segmentation faults)
- */
- // Scalefactors for layer I and II, Annex 3-B.1 in ISO/IEC DIS 11172:
- public static final float scalefactors[] =
- {
- 2.00000000000000f, 1.58740105196820f, 1.25992104989487f, 1.00000000000000f,
- 0.79370052598410f, 0.62996052494744f, 0.50000000000000f, 0.39685026299205f,
- 0.31498026247372f, 0.25000000000000f, 0.19842513149602f, 0.15749013123686f,
- 0.12500000000000f, 0.09921256574801f, 0.07874506561843f, 0.06250000000000f,
- 0.04960628287401f, 0.03937253280921f, 0.03125000000000f, 0.02480314143700f,
- 0.01968626640461f, 0.01562500000000f, 0.01240157071850f, 0.00984313320230f,
- 0.00781250000000f, 0.00620078535925f, 0.00492156660115f, 0.00390625000000f,
- 0.00310039267963f, 0.00246078330058f, 0.00195312500000f, 0.00155019633981f,
- 0.00123039165029f, 0.00097656250000f, 0.00077509816991f, 0.00061519582514f,
- 0.00048828125000f, 0.00038754908495f, 0.00030759791257f, 0.00024414062500f,
- 0.00019377454248f, 0.00015379895629f, 0.00012207031250f, 0.00009688727124f,
- 0.00007689947814f, 0.00006103515625f, 0.00004844363562f, 0.00003844973907f,
- 0.00003051757813f, 0.00002422181781f, 0.00001922486954f, 0.00001525878906f,
- 0.00001211090890f, 0.00000961243477f, 0.00000762939453f, 0.00000605545445f,
- 0.00000480621738f, 0.00000381469727f, 0.00000302772723f, 0.00000240310869f,
- 0.00000190734863f, 0.00000151386361f, 0.00000120155435f, 0.00000000000000f /* illegal scalefactor */
- };
-
- public abstract void read_allocation (Bitstream stream, Header header, Crc16 crc) throws DecoderException;
- public abstract void read_scalefactor (Bitstream stream, Header header);
- public abstract boolean read_sampledata (Bitstream stream);
- public abstract boolean put_next_sample (int channels, SynthesisFilter filter1, SynthesisFilter filter2);
- };
-
- /**
- * Class for layer I subbands in single channel mode.
- * Used for single channel mode
- * and in derived class for intensity stereo mode
- */
- static class SubbandLayer1 extends Subband
- {
-
- // Factors and offsets for sample requantization
- public static final float table_factor[] = {
- 0.0f, (1.0f/2.0f) * (4.0f/3.0f), (1.0f/4.0f) * (8.0f/7.0f), (1.0f/8.0f) * (16.0f/15.0f),
- (1.0f/16.0f) * (32.0f/31.0f), (1.0f/32.0f) * (64.0f/63.0f), (1.0f/64.0f) * (128.0f/127.0f),
- (1.0f/128.0f) * (256.0f/255.0f), (1.0f/256.0f) * (512.0f/511.0f),
- (1.0f/512.0f) * (1024.0f/1023.0f), (1.0f/1024.0f) * (2048.0f/2047.0f),
- (1.0f/2048.0f) * (4096.0f/4095.0f), (1.0f/4096.0f) * (8192.0f/8191.0f),
- (1.0f/8192.0f) * (16384.0f/16383.0f), (1.0f/16384.0f) * (32768.0f/32767.0f)
- };
-
- public static final float table_offset[] = {
- 0.0f, ((1.0f/2.0f)-1.0f) * (4.0f/3.0f), ((1.0f/4.0f)-1.0f) * (8.0f/7.0f), ((1.0f/8.0f)-1.0f) * (16.0f/15.0f),
- ((1.0f/16.0f)-1.0f) * (32.0f/31.0f), ((1.0f/32.0f)-1.0f) * (64.0f/63.0f), ((1.0f/64.0f)-1.0f) * (128.0f/127.0f),
- ((1.0f/128.0f)-1.0f) * (256.0f/255.0f), ((1.0f/256.0f)-1.0f) * (512.0f/511.0f),
- ((1.0f/512.0f)-1.0f) * (1024.0f/1023.0f), ((1.0f/1024.0f)-1.0f) * (2048.0f/2047.0f),
- ((1.0f/2048.0f)-1.0f) * (4096.0f/4095.0f), ((1.0f/4096.0f)-1.0f) * (8192.0f/8191.0f),
- ((1.0f/8192.0f)-1.0f) * (16384.0f/16383.0f), ((1.0f/16384.0f)-1.0f) * (32768.0f/32767.0f)
- };
-
- protected int subbandnumber;
- protected int samplenumber;
- protected int allocation;
- protected float scalefactor;
- protected int samplelength;
- protected float sample;
- protected float factor, offset;
-
- /**
- * Construtor.
- */
- public SubbandLayer1(int subbandnumber)
- {
- this.subbandnumber = subbandnumber;
- samplenumber = 0;
- }
-
- /**
- *
- */
- public void read_allocation(Bitstream stream, Header header, Crc16 crc) throws DecoderException
- {
- if ((allocation = stream.get_bits (4)) == 15)
- {
- // CGJ: catch this condition and throw appropriate exception
- throw new DecoderException(DecoderErrors.ILLEGAL_SUBBAND_ALLOCATION, null);
- // cerr << "WARNING: stream contains an illegal allocation!\n";
- // MPEG-stream is corrupted!
- }
-
- if (crc != null) crc.add_bits (allocation, 4);
- if (allocation != 0)
- {
- samplelength = allocation + 1;
- factor = table_factor[allocation];
- offset = table_offset[allocation];
- }
- }
-
- /**
- *
- */
- public void read_scalefactor(Bitstream stream, Header header)
- {
- if (allocation != 0) scalefactor = scalefactors[stream.get_bits(6)];
- }