VIDEO: Add a PlayStation stream decoder

To be used for sword1/sword2 PSX video playback

1 files changed, 638 insertions, 0 deletions

diff --git a/video/psx_decoder.cpp b/video/psx_decoder.cpp
new file mode 100644
index 0000000000..4ed5a16294
--- /dev/null
+++ b/video/psx_decoder.cpp
@@ -0,0 +1,638 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+// PlayStation Stream demuxer and XA audio decoder based on FFmpeg/libav
+// MDEC video emulation based on http://kenai.com/downloads/jpsxdec/Old/PlayStation1_STR_format1-00.txt
+
+#include "audio/audiostream.h"
+#include "audio/mixer.h"
+#include "audio/decoders/raw.h"
+#include "common/bitstream.h"
+#include "common/huffman.h"
+#include "common/memstream.h"
+#include "common/stream.h"
+#include "common/system.h"
+#include "common/textconsole.h"
+#include "graphics/yuv_to_rgb.h"
+
+#include "video/psx_decoder.h"
+
+namespace Video {
+
+PSXStreamDecoder::PSXStreamDecoder(Common::Rational frameRate) {
+	assert(frameRate != 0);
+	initCommon();
+	_frameRate = frameRate;
+	_frameCount = 0;
+	_speed = kCDUnk;
+}
+
+PSXStreamDecoder::PSXStreamDecoder(CDSpeed speed, uint32 frameCount) {
+	assert(speed != kCDUnk);
+	assert(frameCount != 0);
+	initCommon();
+	_frameCount = frameCount;
+	_speed = speed;
+	// frame rate will be calculated in loadStream()
+}
+
+PSXStreamDecoder::~PSXStreamDecoder() {
+	close();
+	delete _surface;
+	delete _huffman;
+}
+
+#define CODE_COUNT 113
+#define HUFFVAL(z, a) ((z << 8) | a)
+#define ESCAPE_CODE  ((uint32)-1) // arbitrary, just so we can tell what code it is
+#define END_OF_BLOCK ((uint32)-2) // arbitrary, just so we can tell what code it is
+#define GET_ZEROES(code) (code >> 8)
+#define GET_AC(code) ((int)(code & 0xff))
+
+static const uint32 s_huffmanCodes[CODE_COUNT] = {
+	// Regular codes
+	3, 3, 4, 5, 5, 6, 7, 4, 5, 6, 7, 4, 5, 6, 7,
+	32, 33, 34, 35, 36, 37, 38, 39, 8, 9, 10, 11,
+	12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
+	23, 24, 25, 26, 27, 28, 29, 30, 31, 16, 17,
+	18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
+	29, 30, 31, 16, 17, 18, 19, 20, 21, 22, 23,
+	24, 25, 26, 27, 28, 29, 30, 31, 16, 17, 18,
+	19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+	30, 31, 16, 17, 18, 19, 20, 21, 22, 23, 24,
+	25, 26, 27, 28, 29, 30, 31,
+
+	// Escape code
+	1,
+	// End of block code
+	2
+};
+
+static const byte s_huffmanLengths[CODE_COUNT] = {
+	// Regular codes
+	2, 3, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
+	8, 8, 8, 8, 8, 8, 8, 8, 10, 10, 10, 10, 10,
+	10, 10, 10, 12, 12, 12, 12, 12, 12, 12, 12,
+	12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13,
+	13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+	13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+	14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15,
+	15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+	15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+	16, 16, 16, 16, 16, 16,
+
+	// Escape code
+	6,
+	// End of block code
+	2
+};
+
+static const uint32 s_huffmanSymbols[CODE_COUNT] = {
+	// Regular codes
+	HUFFVAL(0, 1), HUFFVAL(1, 1), HUFFVAL(0, 2), HUFFVAL(2, 1), HUFFVAL(0, 3),
+	HUFFVAL(4, 1), HUFFVAL(3, 1), HUFFVAL(7, 1), HUFFVAL(6, 1), HUFFVAL(1, 2),
+	HUFFVAL(5, 1), HUFFVAL(2, 2), HUFFVAL(9, 1), HUFFVAL(0, 4), HUFFVAL(8, 1),
+	HUFFVAL(13, 1), HUFFVAL(0, 6), HUFFVAL(12, 1), HUFFVAL(11, 1), HUFFVAL(3, 2),
+	HUFFVAL(1, 3), HUFFVAL(0, 5), HUFFVAL(10, 1), HUFFVAL(16, 1), HUFFVAL(5, 2),
+	HUFFVAL(0, 7), HUFFVAL(2, 3), HUFFVAL(1, 4), HUFFVAL(15, 1), HUFFVAL(14, 1),
+	HUFFVAL(4, 2), HUFFVAL(0, 11), HUFFVAL(8, 2), HUFFVAL(4, 3), HUFFVAL(0, 10),
+	HUFFVAL(2, 4), HUFFVAL(7, 2), HUFFVAL(21, 1), HUFFVAL(20, 1), HUFFVAL(0, 9),
+	HUFFVAL(19, 1), HUFFVAL(18, 1), HUFFVAL(1, 5), HUFFVAL(3, 3), HUFFVAL(0, 8),
+	HUFFVAL(6, 2), HUFFVAL(17, 1), HUFFVAL(10, 2), HUFFVAL(9, 2), HUFFVAL(5, 3),
+	HUFFVAL(3, 4), HUFFVAL(2, 5), HUFFVAL(1, 7), HUFFVAL(1, 6), HUFFVAL(0, 15),
+	HUFFVAL(0, 14), HUFFVAL(0, 13), HUFFVAL(0, 12), HUFFVAL(26, 1), HUFFVAL(25, 1),
+	HUFFVAL(24, 1), HUFFVAL(23, 1), HUFFVAL(22, 1), HUFFVAL(0, 31), HUFFVAL(0, 30),
+	HUFFVAL(0, 29), HUFFVAL(0, 28), HUFFVAL(0, 27), HUFFVAL(0, 26), HUFFVAL(0, 25),
+	HUFFVAL(0, 24), HUFFVAL(0, 23), HUFFVAL(0, 22), HUFFVAL(0, 21), HUFFVAL(0, 20),
+	HUFFVAL(0, 19), HUFFVAL(0, 18), HUFFVAL(0, 17), HUFFVAL(0, 16), HUFFVAL(0, 40),
+	HUFFVAL(0, 39), HUFFVAL(0, 38), HUFFVAL(0, 37), HUFFVAL(0, 36), HUFFVAL(0, 35),
+	HUFFVAL(0, 34), HUFFVAL(0, 33), HUFFVAL(0, 32), HUFFVAL(1, 14), HUFFVAL(1, 13),
+	HUFFVAL(1, 12), HUFFVAL(1, 11), HUFFVAL(1, 10), HUFFVAL(1, 9), HUFFVAL(1, 8),
+	HUFFVAL(1, 18), HUFFVAL(1, 17), HUFFVAL(1, 16), HUFFVAL(1, 15), HUFFVAL(6, 3),
+	HUFFVAL(16, 2), HUFFVAL(15, 2), HUFFVAL(14, 2), HUFFVAL(13, 2), HUFFVAL(12, 2),
+	HUFFVAL(11, 2), HUFFVAL(31, 1), HUFFVAL(30, 1), HUFFVAL(29, 1), HUFFVAL(28, 1),
+	HUFFVAL(27, 1),
+
+	// Escape code
+	ESCAPE_CODE,
+	// End of block code
+	END_OF_BLOCK
+};
+
+void PSXStreamDecoder::initCommon() {
+	_stream = 0;
+	_audStream = 0;
+	_surface = new Graphics::Surface();
+	_yBuffer = _cbBuffer = _crBuffer = 0;
+	_huffman = new Common::Huffman(0, CODE_COUNT, s_huffmanCodes, s_huffmanLengths, s_huffmanSymbols);
+}
+
+#define RAW_CD_SECTOR_SIZE 2352
+
+#define CDXA_TYPE_MASK     0x0E
+#define CDXA_TYPE_DATA     0x08
+#define CDXA_TYPE_AUDIO    0x04
+#define CDXA_TYPE_VIDEO    0x02
+
+bool PSXStreamDecoder::loadStream(Common::SeekableReadStream *stream) {
+	close();
+
+	_stream = stream;
+
+	Common::SeekableReadStream *sector = readSector();
+
+	if (!sector) {
+		close();
+		return false;
+	}
+
+	// Rip out video info from the first frame
+	sector->seek(18);
+	byte sectorType = sector->readByte() & CDXA_TYPE_MASK;
+
+	if (sectorType != CDXA_TYPE_VIDEO && sectorType != CDXA_TYPE_DATA) {
+		close();
+		return false;
+	}
+
+	sector->seek(40);
+
+	uint16 width = sector->readUint16LE();
+	uint16 height = sector->readUint16LE();
+	_surface->create(width, height, g_system->getScreenFormat());
+
+	_macroBlocksW = (width + 15) / 16;
+	_macroBlocksH = (height + 15) / 16;
+	_yBuffer = new byte[_macroBlocksW * _macroBlocksH * 16 * 16];
+	_cbBuffer = new byte[_macroBlocksW * _macroBlocksH * 8 * 8];
+	_crBuffer = new byte[_macroBlocksW * _macroBlocksH * 8 * 8];
+
+	delete sector;
+	_stream->seek(0);
+
+	// Calculate frame rate based on CD speed
+	if (_speed != kCDUnk) {
+		// TODO: This algorithm is too basic and not accurate enough
+		// TODO: Count the number of sectors per frame to get a better estimate
+		_frameRate = Common::Rational(_speed * _frameCount, _stream->size() / RAW_CD_SECTOR_SIZE);
+		_frameRate.debugPrint(0, "Approximate PSX Stream Frame Rate:");
+	}
+
+	return true;
+}
+
+void PSXStreamDecoder::close() {
+	if (!_stream)
+		return;
+
+	delete _stream;
+	_stream = 0;
+
+	// Deinitialize sound
+	g_system->getMixer()->stopHandle(_audHandle);
+	_audStream = 0;
+
+	_surface->free();
+
+	memset(&_adpcmStatus, 0, sizeof(_adpcmStatus));
+
+	_macroBlocksW = _macroBlocksH = 0;
+	delete[] _yBuffer; _yBuffer = 0;
+	delete[] _cbBuffer; _cbBuffer = 0;
+	delete[] _crBuffer; _crBuffer = 0;
+
+	reset();
+}
+
+uint32 PSXStreamDecoder::getElapsedTime() const {
+	// TODO: Currently, the audio is always after the video so using this
+	// can often lead to gaps in the audio...
+	//if (_audStream)
+	//	return _mixer->getSoundElapsedTime(_audHandle);
+
+	return FixedRateVideoDecoder::getElapsedTime();
+}
+
+#define VIDEO_DATA_CHUNK_SIZE   2016
+#define VIDEO_DATA_HEADER_SIZE  56
+
+const Graphics::Surface *PSXStreamDecoder::decodeNextFrame() {
+	Common::SeekableReadStream *sector = 0;
+	byte *partialFrame = 0;
+
+	while (!endOfVideo()) {
+		sector = readSector();
+
+		if (!sector)
+			error("Corrupt PSX stream sector");
+
+		sector->seek(0x11);
+		byte track = sector->readByte();
+		if (track >= 32)
+			error("Bad PSX stream track");
+
+		byte sectorType = sector->readByte() & CDXA_TYPE_MASK;
+
+		switch (sectorType) {
+		case CDXA_TYPE_DATA:
+		case CDXA_TYPE_VIDEO:
+			if (track == 1) {
+				sector->seek(28);
+				uint16 curSector = sector->readUint16LE();
+				uint16 sectorCount = sector->readUint16LE();
+				sector->readUint32LE();
+				uint16 frameSize = sector->readUint32LE();
+
+				if (curSector >= sectorCount)
+					error("Bad sector");
+
+				if (!partialFrame)
+					partialFrame = (byte *)malloc(sectorCount * VIDEO_DATA_CHUNK_SIZE);
+
+				sector->seek(VIDEO_DATA_HEADER_SIZE);
+				sector->read(partialFrame + curSector * VIDEO_DATA_CHUNK_SIZE, VIDEO_DATA_CHUNK_SIZE);
+
+				if (curSector == sectorCount - 1) {
+					// Done assembling the frame
+					Common::SeekableReadStream *frame = new Common::MemoryReadStream(partialFrame, frameSize, DisposeAfterUse::YES);
+
+					decodeFrame(frame);
+					
+					delete frame;
+					delete sector;
+
+					_curFrame++;
+					if (_curFrame == 0)
+						_startTime = g_system->getMillis();
+
+					return _surface;
+				}
+			} else
+				error("Unhandled multi-track video");
+			break;
+		case CDXA_TYPE_AUDIO:
+			// We only handle one audio channel so far
+			if (track == 1)
+				queueAudioFromSector(sector);
+			else
+				warning("Unhandled multi-track audio");
+			break;
+		default:
+			// This shows up way too often, but the other sectors
+			// are safe to ignore
+			//warning("Unknown PSX sector type 0x%x", sectorType);
+			break;
+		}
+
+		delete sector;
+	}
+
+	return 0;
+}
+
+static const byte s_syncHeader[12] = { 0x00, 0xff ,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00 };
+
+Common::SeekableReadStream *PSXStreamDecoder::readSector() {
+	assert(_stream);
+
+	Common::SeekableReadStream *stream = _stream->readStream(RAW_CD_SECTOR_SIZE);
+
+	byte syncHeader[12];
+	stream->read(syncHeader, 12);
+	if (!memcmp(s_syncHeader, syncHeader, 12))
+		return stream;
+
+	return 0;
+}
+
+// Ha! It's palindromic!
+#define AUDIO_DATA_CHUNK_SIZE   2304
+#define AUDIO_DATA_SAMPLE_COUNT 4032 
+
+static const int s_xaTable[5][2] = {
+   {   0,   0 },
+   {  60,   0 },
+   { 115, -52 },
+   {  98, -55 },
+   { 122, -60 }
+};
+
+void PSXStreamDecoder::queueAudioFromSector(Common::SeekableReadStream *sector) {
+	assert(sector);
+
+	if (!_audStream) {
+		// Initialize audio stream
+		sector->seek(19);
+		byte format = sector->readByte();
+
+		bool stereo = (format & (1 << 0)) != 0;
+		uint rate = (format & (1 << 2)) ? 18900 : 37800;
+
+		_audStream = Audio::makeQueuingAudioStream(rate, stereo);
+		g_system->getMixer()->playStream(Audio::Mixer::kPlainSoundType, &_audHandle, _audStream);
+	}
+
+	sector->seek(24);
+
+	// This XA audio is different (yet similar) from normal XA audio! Watch out!
+	// TODO: It's probably similar enough to normal XA that we can merge it somehow...
+	// TODO: RTZ PSX needs the same audio code in a regular AudioStream class. Probably
+	// will do something similar to QuickTime and creating a base class 'ISOMode2Parser'
+	// or something similar.
+	byte *buf = new byte[AUDIO_DATA_CHUNK_SIZE];
+	sector->read(buf, AUDIO_DATA_CHUNK_SIZE);
+
+	int channels = _audStream->isStereo() ? 2 : 1;
+	int16 *dst = new int16[AUDIO_DATA_SAMPLE_COUNT];
+	int16 *leftChannel = dst;
+	int16 *rightChannel = dst + 1;
+
+	for (byte *src = buf; src < buf + AUDIO_DATA_CHUNK_SIZE; src += 128) {
+		for (int i = 0; i < 4; i++) {
+			int shift = 12 - (src[4 + i * 2] & 0xf);
+			int filter = src[4 + i * 2] >> 4;
+			int f0 = s_xaTable[filter][0];
+			int f1 = s_xaTable[filter][1];
+			int16 s_1 = _adpcmStatus[0].sample[0];
+			int16 s_2 = _adpcmStatus[0].sample[1];
+
+			for (int j = 0; j < 28; j++) {
+				byte d = src[16 + i + j * 4];
+				int t = (int8)(d << 4) >> 4;
+				int s = (t << shift) + ((s_1 * f0 + s_2 * f1 + 32) >> 6);
+				s_2 = s_1;
+				s_1 = CLIP<int>(s, -32768, 32767);
+				*leftChannel = s_1;
+				leftChannel += channels;
+			}
+
+			if (channels == 2) {
+				_adpcmStatus[0].sample[0] = s_1;
+				_adpcmStatus[0].sample[1] = s_2;
+				s_1 = _adpcmStatus[1].sample[0];
+				s_2 = _adpcmStatus[1].sample[1];
+			}
+
+			shift = 12 - (src[5 + i * 2] & 0xf);
+			filter = src[5 + i * 2] >> 4;
+			f0 = s_xaTable[filter][0];
+			f1 = s_xaTable[filter][1];
+
+			for (int j = 0; j < 28; j++) {
+				byte d = src[16 + i + j * 4];
+				int t = (int8)d >> 4;
+				int s = (t << shift) + ((s_1 * f0 + s_2 * f1 + 32) >> 6);
+				s_2 = s_1;
+				s_1 = CLIP<int>(s, -32768, 32767);
+
+				if (channels == 2) {
+					*rightChannel = s_1;
+					rightChannel += 2;
+				} else {
+					*leftChannel++ = s_1;
+				}
+			}
+
+			if (channels == 2) {
+				_adpcmStatus[1].sample[0] = s_1;
+				_adpcmStatus[1].sample[1] = s_2;
+			} else {
+				_adpcmStatus[0].sample[0] = s_1;
+				_adpcmStatus[0].sample[1] = s_2;
+			}
+		}
+	}
+
+	int flags = Audio::FLAG_16BITS;
+
+	if (_audStream->isStereo())
+		flags |= Audio::FLAG_STEREO;
+
+#ifdef SCUMM_LITTLE_ENDIAN
+	flags |= Audio::FLAG_LITTLE_ENDIAN;
+#endif
+
+	_audStream->queueBuffer((byte *)dst, AUDIO_DATA_SAMPLE_COUNT * 2, DisposeAfterUse::YES, flags);
+	delete[] buf;
+}
+
+void PSXStreamDecoder::decodeFrame(Common::SeekableReadStream *frame) {
+	// A frame is essentially an MPEG-1 intra frame
+
+	Common::BitStream16LEMSB bits(frame);
+
+	bits.skip(16); // unknown
+	bits.skip(16); // 0x3800
+	uint16 scale = bits.getBits(16);
+	uint16 version = bits.getBits(16);
+
+	if (version != 2 && version != 3)
+		error("Unknown PSX stream frame version");
+
+	for (int mbX = 0; mbX < _macroBlocksW; mbX++)
+		for (int mbY = 0; mbY < _macroBlocksH; mbY++)
+			decodeMacroBlock(&bits, mbX, mbY, scale, version);
+
+	// Output data onto the frame
+	Graphics::convertYUV420ToRGB(_surface, _yBuffer, _cbBuffer, _crBuffer, _surface->w, _surface->h, _macroBlocksW * 16, _macroBlocksW * 8);
+}
+
+void PSXStreamDecoder::decodeMacroBlock(Common::BitStream *bits, int mbX, int mbY, uint16 scale, uint16 version) {
+	int pitchY = _macroBlocksW * 16;
+	int pitchC = _macroBlocksW * 8;
+
+	// Note the strange order of red before blue
+	decodeBlock(bits, _crBuffer + (mbY * pitchC + mbX) * 8, pitchC, scale, version);
+	decodeBlock(bits, _cbBuffer + (mbY * pitchC + mbX) * 8, pitchC, scale, version);
+	decodeBlock(bits, _yBuffer + (mbY * pitchY + mbX) * 16, pitchY, scale, version);
+	decodeBlock(bits, _yBuffer + (mbY * pitchY + mbX) * 16 + 8, pitchY, scale, version);
+	decodeBlock(bits, _yBuffer + (mbY * pitchY + mbX) * 16 + 8 * pitchY, pitchY, scale, version);
+	decodeBlock(bits, _yBuffer + (mbY * pitchY + mbX) * 16 + 8 * pitchY + 8, pitchY, scale, version);
+}
+
+// Standard JPEG/MPEG zig zag table
+static const byte s_zigZagTable[8 * 8] = {
+	 0,  1,  5,  6, 14, 15, 27, 28,
+	 2,  4,  7, 13, 16, 26, 29, 42,
+	 3,  8, 12, 17, 25, 30, 41, 43,
+	 9, 11, 18, 24, 31, 40, 44, 53,
+	10, 19, 23, 32, 39, 45, 52, 54,
+	20, 22, 33, 38, 46, 51, 55, 60,
+	21, 34, 37, 47, 50, 56, 59, 61,
+	35, 36, 48, 49, 57, 58, 62, 63
+};
+
+// One byte different from the standard MPEG-1 table
+static const byte s_quantizationTable[8 * 8] = {
+	 2, 16, 19, 22, 26, 27, 29, 34,
+	16, 16, 22, 24, 27, 29, 34, 37,
+	19, 22, 26, 27, 29, 34, 34, 38,
+	22, 22, 26, 27, 29, 34, 37, 40,
+	22, 26, 27, 29, 32, 35, 40, 48,
+	26, 27, 29, 32, 35, 40, 48, 58,
+	26, 27, 29, 34, 38, 46, 56, 69,
+	27, 29, 35, 38, 46, 56, 69, 83
+};
+
+void PSXStreamDecoder::dequantizeBlock(int *coefficients, float *block, uint16 scale) {
+	// Dequantize the data, un-zig-zagging as we go along
+	for (int i = 0; i < 8 * 8; i++) {
+		if (i == 0) // Special case for the DC coefficient
+			block[i] = coefficients[i] * s_quantizationTable[i];
+		else
+			block[i] = (float)coefficients[s_zigZagTable[i]] * s_quantizationTable[i] * scale / 8;
+	}
+}
+
+#define BLOCK_OVERFLOW_CHECK() \
+	if (count > 63) \
+		error("PSXStreamDecoder::readAC(): Too many coefficients")
+
+void PSXStreamDecoder::readAC(Common::BitStream *bits, int *block) {
+	// Clear the block first
+	for (int i = 0; i < 63; i++)
+		block[i] = 0;
+
+	int count = 0;
+
+	while (!bits->eos()) {
+		uint32 symbol = _huffman->getSymbol(*bits);
+
+		if (symbol == ESCAPE_CODE) {
+			// The escape code!
+			int zeroes = bits->getBits(6);
+			count += zeroes + 1;
+			BLOCK_OVERFLOW_CHECK();
+			block += zeroes;
+			*block++ = readSignedCoefficient(bits);
+		} else if (symbol == END_OF_BLOCK) {
+			// We're done
+			break;
+		} else {
+			// Normal huffman code
+			int zeroes = GET_ZEROES(symbol);
+			count += zeroes + 1;
+			BLOCK_OVERFLOW_CHECK();
+			block += zeroes;
+
+			if (bits->getBit())
+				*block++ = -GET_AC(symbol);
+			else
+				*block++ = GET_AC(symbol);
+		}
+	}
+}
+
+int PSXStreamDecoder::readSignedCoefficient(Common::BitStream *bits) {
+	uint val = bits->getBits(10);
+
+	// extend the sign
+	uint shift = 8 * sizeof(int) - 10;
+	return (int)(val << shift) >> shift;
+}
+
+// IDCT table built with :
+// _idct8x8[x][y] = cos(((2 * x + 1) * y) * (M_PI / 16.0)) * 0.5;
+// _idct8x8[x][y] /= sqrt(2.0) if y == 0
+static const double s_idct8x8[8][8] = {
+	{ 0.353553390593274,  0.490392640201615,  0.461939766255643,  0.415734806151273,  0.353553390593274,  0.277785116509801,  0.191341716182545,  0.097545161008064 },
+	{ 0.353553390593274,  0.415734806151273,  0.191341716182545, -0.097545161008064, -0.353553390593274, -0.490392640201615, -0.461939766255643, -0.277785116509801 },
+	{ 0.353553390593274,  0.277785116509801, -0.191341716182545, -0.490392640201615, -0.353553390593274,  0.097545161008064,  0.461939766255643,  0.415734806151273 },
+	{ 0.353553390593274,  0.097545161008064, -0.461939766255643, -0.277785116509801,  0.353553390593274,  0.415734806151273, -0.191341716182545, -0.490392640201615 },
+	{ 0.353553390593274, -0.097545161008064, -0.461939766255643,  0.277785116509801,  0.353553390593274, -0.415734806151273, -0.191341716182545,  0.490392640201615 },
+	{ 0.353553390593274, -0.277785116509801, -0.191341716182545,  0.490392640201615, -0.353553390593273, -0.097545161008064,  0.461939766255643, -0.415734806151273 },
+	{ 0.353553390593274, -0.415734806151273,  0.191341716182545,  0.097545161008064, -0.353553390593274,  0.490392640201615, -0.461939766255643,  0.277785116509801 },
+	{ 0.353553390593274, -0.490392640201615,  0.461939766255643, -0.415734806151273,  0.353553390593273, -0.277785116509801,  0.191341716182545, -0.097545161008064 }
+};
+
+void PSXStreamDecoder::idct(float *dequantData, float *result) {
+	// IDCT code based on JPEG's IDCT code
+	// TODO: Switch to the integer-based one mentioned in the docs
+	// This is by far the costliest operation here
+
+	float tmp[8 * 8];
+
+	// Apply 1D IDCT to rows
+	for (int y = 0; y < 8; y++) {
+		for (int x = 0; x < 8; x++) {
+			tmp[y + x * 8] = dequantData[0] * s_idct8x8[x][0]
+							+ dequantData[1] * s_idct8x8[x][1]
+							+ dequantData[2] * s_idct8x8[x][2]
+							+ dequantData[3] * s_idct8x8[x][3]
+							+ dequantData[4] * s_idct8x8[x][4]
+							+ dequantData[5] * s_idct8x8[x][5]
+							+ dequantData[6] * s_idct8x8[x][6]
+							+ dequantData[7] * s_idct8x8[x][7];
+		}
+
+		dequantData += 8;
+	}
+
+	// Apply 1D IDCT to columns
+	for (int x = 0; x < 8; x++) {
+		const float *u = tmp + x * 8;
+		for (int y = 0; y < 8; y++) {
+			result[y * 8 + x] = u[0] * s_idct8x8[y][0]
+								+ u[1] * s_idct8x8[y][1]
+								+ u[2] * s_idct8x8[y][2]
+								+ u[3] * s_idct8x8[y][3]
+								+ u[4] * s_idct8x8[y][4]
+								+ u[5] * s_idct8x8[y][5]
+								+ u[6] * s_idct8x8[y][6]
+								+ u[7] * s_idct8x8[y][7];
+		}
+	}
+}
+
+void PSXStreamDecoder::decodeBlock(Common::BitStream *bits, byte *block, int pitch, uint16 scale, uint16 version) {
+	int dc;
+
+	if (version == 2) {
+		dc = readSignedCoefficient(bits);
+	} else {
+		// TODO
+		error("Unhandled PSX stream version 3 DC");
+	}
+
+	int coefficients[8 * 8];
+	coefficients[0] = dc; // Start us off with the DC
+	readAC(bits, &coefficients[1]); // Read in the AC
+
+	// Dequantize
+	float dequantData[8 * 8];
+	dequantizeBlock(coefficients, dequantData, scale);
+
+	// Perform IDCT
+	float idctData[8 * 8];
+	idct(dequantData, idctData);
+
+	// Now output the data
+	for (int y = 0; y < 8; y++) {
+		byte *start = block + pitch * y;
+
+		// Convert the result to be in the range [0, 255]
+		for (int x = 0; x < 8; x++)
+			*start++ = (int)CLIP<float>(idctData[y * 8 + x], -128.0f, 127.0f) + 128;
+	}
+}
+
+} // End of namespace Video