/***************************************************************************

    avhuff.c

    Audio/video compression and decompression helpers.

****************************************************************************

    Copyright Aaron Giles
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.
        * Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.
        * Neither the name 'MAME' nor the names of its contributors may be
          used to endorse or promote products derived from this software
          without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT,
    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
    IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

****************************************************************************

    Each frame is compressed as a unit. The raw data is of the form:
    (all multibyte values are stored in big-endian format)

        +00 = 'chav' (4 bytes) - fixed header data to identify the format
        +04 = metasize (1 byte) - size of metadata in bytes (max=255 bytes)
        +05 = channels (1 byte) - number of audio channels
        +06 = samples (2 bytes) - number of samples per audio stream
        +08 = width (2 bytes) - width of video data
        +0A = height (2 bytes) - height of video data
        +0C = <metadata> - as raw bytes
              <audio stream 0> - as signed 16-bit samples
              <audio stream 1> - as signed 16-bit samples
              ...
              <video data> - as a raw array of 8-bit YUY data in (Cb,Y,Cr,Y) order

    When compressed, the data is stored as follows:
    (all multibyte values are stored in big-endian format)

        +00 = metasize (1 byte) - size of metadata in bytes
        +01 = channels (1 byte) - number of audio channels
        +02 = samples (2 bytes) - number of samples per audio stream
        +04 = width (2 bytes) - width of video data
        +06 = height (2 bytes) - height of video data
        +08 = audio huffman size (2 bytes) - size of audio huffman tables
                (0x0000 => uncompressed deltas are used)
        +0A = str0size (2 bytes) - compressed size of stream 0
        +0C = str1size (2 bytes) - compressed size of stream 1
              ...
              <metadata> - as raw data
              <audio huffman table> - Huffman table for audio decoding
              <audio stream 0 data> - Huffman-compressed deltas
              <audio stream 1 data> - Huffman-compressed deltas
              <...>
              <video huffman tables> - Huffman tables for video decoding
              <video data> - compressed data

****************************************************************************

    Attempted techniques that have not been worthwhile:

    * Attempted to use integer DCTs from the IJG code; even the "slow"
      variants produce a lot of error and thus kill our compression ratio,
      since our compression is based on error not bitrate.

    * Tried various other predictors for the lossless video encoding, but
      none tended to give any significant gain over predicting the
      previous pixel.

***************************************************************************/

#include "avhuff.h"
#include "huffman.h"
#include "chd.h"

#include <math.h>
#include <stdlib.h>
#include <new>



//**************************************************************************
//  INLINE FUNCTIONS
//**************************************************************************

//-------------------------------------------------
//  code_to_rlecount - number of RLE repetitions
//  encoded in a given byte
//-------------------------------------------------

inline int code_to_rlecount(int code)
{
	if (code == 0x00)
		return 1;
	if (code <= 0x107)
		return 8 + (code - 0x100);
	return 16 << (code - 0x108);
}


//-------------------------------------------------
//  rlecount_to_byte - return a byte encoding
//  the maximum RLE count less than or equal to
//  the provided amount
//-------------------------------------------------

inline int rlecount_to_code(int rlecount)
{
	if (rlecount >= 2048)
		return 0x10f;
	if (rlecount >= 1024)
		return 0x10e;
	if (rlecount >= 512)
		return 0x10d;
	if (rlecount >= 256)
		return 0x10c;
	if (rlecount >= 128)
		return 0x10b;
	if (rlecount >= 64)
		return 0x10a;
	if (rlecount >= 32)
		return 0x109;
	if (rlecount >= 16)
		return 0x108;
	if (rlecount >= 8)
		return 0x100 + (rlecount - 8);
	return 0x00;
}


//-------------------------------------------------
//  encode_one - encode data
//-------------------------------------------------

inline void avhuff_encoder::deltarle_encoder::encode_one(bitstream_out &bitbuf, UINT16 *&rleptr)
{
	// return RLE data if we still have some
	if (m_rlecount != 0)
	{
		m_rlecount--;
		return;
	}

	// fetch the data and process
	UINT16 data = *rleptr++;
	m_encoder.encode_one(bitbuf, data);
	if (data >= 0x100)
		m_rlecount = code_to_rlecount(data) - 1;
}


//-------------------------------------------------
//  decode_one - decode data
//-------------------------------------------------

inline UINT32 avhuff_decoder::deltarle_decoder::decode_one(bitstream_in &bitbuf)
{
	// return RLE data if we still have some
	if (m_rlecount != 0)
	{
		m_rlecount--;
		return m_prevdata;
	}

	// fetch the data and process
	int data = m_decoder.decode_one(bitbuf);
	if (data < 0x100)
	{
		m_prevdata += UINT8(data);
		return m_prevdata;
	}
	else
	{
		m_rlecount = code_to_rlecount(data);
		m_rlecount--;
		return m_prevdata;
	}
}



//**************************************************************************
//  AVHUFF ENCODER
//**************************************************************************

//-------------------------------------------------
//  avhuff_encoder - constructor
//-------------------------------------------------

avhuff_encoder::avhuff_encoder()
{
m_flac_encoder.set_sample_rate(48000);
m_flac_encoder.set_num_channels(1);
m_flac_encoder.set_strip_metadata(true);
}


//-------------------------------------------------
//  encode_data - encode a block of data into a
//  compressed data stream
//-------------------------------------------------

avhuff_error avhuff_encoder::encode_data(const UINT8 *source, UINT8 *dest, UINT32 &complength)
{
	// validate the header
	if (source[0] != 'c' || source[1] != 'h' || source[2] != 'a' || source[3] != 'v')
		return AVHERR_INVALID_DATA;

	// extract info from the header
	UINT32 metasize = source[4];
	UINT32 channels = source[5];
	UINT32 samples = (source[6] << 8) + source[7];
	UINT32 width = (source[8] << 8) + source[9];
	UINT32 height = (source[10] << 8) + source[11];
	source += 12;

	// write the basics to the new header
	dest[0] = metasize;
	dest[1] = channels;
	dest[2] = samples >> 8;
	dest[3] = samples;
	dest[4] = width >> 8;
	dest[5] = width;
	dest[6] = height >> 8;
	dest[7] = height;

	// starting offsets
	UINT32 dstoffs = 10 + 2 * channels;

	// copy the metadata first
	if (metasize > 0)
	{
		memcpy(dest + dstoffs, source, metasize);
		source += metasize;
		dstoffs += metasize;
	}

	// encode the audio channels
	if (channels > 0)
	{
		// encode the audio
		avhuff_error err = encode_audio(source, channels, samples, dest + dstoffs, &dest[8]);
		source += channels * samples * 2;
		if (err != AVHERR_NONE)
			return err;

		// advance the pointers past the data
		UINT16 treesize = (dest[8] << 8) + dest[9];
		if (treesize != 0xffff)
			dstoffs += treesize;
		for (int chnum = 0; chnum < channels; chnum++)
			dstoffs += (dest[10 + 2 * chnum] << 8) + dest[11 + 2 * chnum];
	}

	// encode the video data
	if (width > 0 && height > 0)
	{
		// encode the video
		UINT32 vidlength = 0;
		avhuff_error err = encode_video(source, width, height, dest + dstoffs, vidlength);
		if (err != AVHERR_NONE)
			return err;

		// advance the pointers past the data
		dstoffs += vidlength;
	}

	// set the total compression
	complength = dstoffs;
	return AVHERR_NONE;
}


//-------------------------------------------------
//  raw_data_size - return the raw data size of
//  a raw stream based on the header
//-------------------------------------------------

UINT32 avhuff_encoder::raw_data_size(const UINT8 *data)
{
	// make sure we have a correct header
	int size = 0;
	if (data[0] == 'c' && data[1] == 'h' && data[2] == 'a' && data[3] == 'v')
	{
		// add in header size plus metadata length
		size = 12 + data[4];

		// add in channels * samples
		size += 2 * data[5] * ((data[6] << 8) + data[7]);

		// add in 2 * width * height
		size += 2 * ((data[8] << 8) + data[9]) * (((data[10] << 8) + data[11]) & 0x7fff);
	}
	return size;
}


//-------------------------------------------------
//  assemble_data - assemble a datastream from raw
//  bits
//-------------------------------------------------

avhuff_error avhuff_encoder::assemble_data(UINT8 *dest, UINT32 dlength, bitmap_yuy16 &bitmap, UINT8 channels, UINT32 numsamples, INT16 **samples, UINT8 *metadata, UINT32 metadatasize)
{
	// sanity check the inputs
	if (metadatasize > 255)
		return AVHERR_METADATA_TOO_LARGE;
	if (numsamples > 65535)
		return AVHERR_AUDIO_TOO_LARGE;
	if (bitmap.width() > 65535 || bitmap.height() > 65535)
		return AVHERR_VIDEO_TOO_LARGE;
	if (dlength < 12 + metadatasize + numsamples * channels * 2 + bitmap.width() * bitmap.height() * 2)
		return AVHERR_BUFFER_TOO_SMALL;

	// fill in the header
	*dest++ = 'c';
	*dest++ = 'h';
	*dest++ = 'a';
	*dest++ = 'v';
	*dest++ = metadatasize;
	*dest++ = channels;
	*dest++ = numsamples >> 8;
	*dest++ = numsamples & 0xff;
	*dest++ = bitmap.width() >> 8;
	*dest++ = bitmap.width() & 0xff;
	*dest++ = bitmap.height() >> 8;
	*dest++ = bitmap.height() & 0xff;

	// copy the metadata
	if (metadatasize > 0)
		memcpy(dest, metadata, metadatasize);
	dest += metadatasize;

	// copy the audio streams
	for (UINT8 curchan = 0; curchan < channels; curchan++)
		for (UINT32 cursamp = 0; cursamp < numsamples; cursamp++)
		{
			*dest++ = samples[curchan][cursamp] >> 8;
			*dest++ = samples[curchan][cursamp] & 0xff;
		}

	// copy the video data
	for (INT32 y = 0; y < bitmap.height(); y++)
	{
		UINT16 *src = &bitmap.pix(y);
		for (INT32 x = 0; x < bitmap.width(); x++)
		{
			*dest++ = src[x] >> 8;
			*dest++ = src[x] & 0xff;
		}
	}
	return AVHERR_NONE;
}


//-------------------------------------------------
//  encode_audio - encode raw audio data to the
//  destination
//-------------------------------------------------

avhuff_error avhuff_encoder::encode_audio(const UINT8 *source, int channels, int samples, UINT8 *dest, UINT8 *sizes)
{
#if AVHUFF_USE_FLAC

	// input data is big-endian; determine our platform endianness
	UINT16 be_test = 0;
	*(UINT8 *)&be_test = 1;
	bool swap_endian = (be_test == 1);

	// set huffman tree size to 0xffff to indicate FLAC
	sizes[0] = 0xff;
	sizes[1] = 0xff;

	// set the block size for this round and iterate over channels
	m_flac_encoder.set_block_size(samples);
	for (int chnum = 0; chnum < channels; chnum++)
	{
		// encode the data
		m_flac_encoder.reset(dest, samples * 2);
		if (!m_flac_encoder.encode_interleaved(reinterpret_cast<const INT16 *>(source) + chnum * samples, samples, swap_endian))
			return AVHERR_COMPRESSION_ERROR;

		// set the size for this channel
		UINT32 cursize = m_flac_encoder.finish();
		sizes[chnum * 2 + 2] = cursize >> 8;
		sizes[chnum * 2 + 3] = cursize;
		dest += cursize;
	}

#else

	// expand the delta buffer if needed
	m_audiobuffer.resize(channels * samples * 2);
	UINT8 *deltabuf = m_audiobuffer;

	// iterate over channels to compute deltas
	m_audiohi_encoder.histo_reset();
	m_audiolo_encoder.histo_reset();
	for (int chnum = 0; chnum < channels; chnum++)
	{
		// extract audio data into hi and lo deltas stored in big-endian order
		INT16 prevsample = 0;
		for (int sampnum = 0; sampnum < samples; sampnum++)
		{
			INT16 newsample = (source[0] << 8) | source[1];
			source += 2;

			INT16 delta = newsample - prevsample;
			prevsample = newsample;
			m_audiohi_encoder.histo_one(*deltabuf++ = delta >> 8);
			m_audiolo_encoder.histo_one(*deltabuf++ = delta);
		}
	}

	// compute the trees
	huffman_error hufferr = m_audiohi_encoder.compute_tree_from_histo();
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;
	hufferr = m_audiolo_encoder.compute_tree_from_histo();
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;

	// export the trees to the output
	bitstream_out bitbuf(dest, 2 * channels * samples);
	hufferr = m_audiohi_encoder.export_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;
	bitbuf.flush();
	hufferr = m_audiolo_encoder.export_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;

	// note the size of the two trees
	UINT32 huffsize = bitbuf.flush();
	sizes[0] = huffsize >> 8;
	sizes[1] = huffsize;

	// iterate over channels
	UINT32 totalsize = huffsize;
	int chnum;
	for (chnum = 0; chnum < channels; chnum++)
	{
		// encode the data
		const UINT8 *input = m_audiobuffer + chnum * samples * 2;
		for (int sampnum = 0; sampnum < samples; sampnum++)
		{
			m_audiohi_encoder.encode_one(bitbuf, *input++);
			m_audiolo_encoder.encode_one(bitbuf, *input++);
		}

		// store the size of this stream
		UINT32 cursize = bitbuf.flush() - totalsize;
		totalsize += cursize;
		if (totalsize >= channels * samples * 2)
			break;
		sizes[chnum * 2 + 2] = cursize >> 8;
		sizes[chnum * 2 + 3] = cursize;
	}

	// if we ran out of room, throw it all away and just store raw
	if (chnum < channels)
	{
		memcpy(dest, m_audiobuffer, channels * samples * 2);
		UINT32 size = samples * 2;
		sizes[0] = sizes[1] = 0;
		for (chnum = 0; chnum < channels; chnum++)
		{
			sizes[chnum * 2 + 2] = size >> 8;
			sizes[chnum * 2 + 3] = size;
		}
	}

#endif

	return AVHERR_NONE;
}


//-------------------------------------------------
//  encode_video - encode raw video data to the
//  destination
//-------------------------------------------------

avhuff_error avhuff_encoder::encode_video(const UINT8 *source, int width, int height, UINT8 *dest, UINT32 &complength)
{
	// only lossless supported at this time
	return encode_video_lossless(source, width, height, dest, complength);
}


//-------------------------------------------------
//  encode_video_lossless - do a lossless video
//  encoding using deltas and huffman encoding
//-------------------------------------------------

avhuff_error avhuff_encoder::encode_video_lossless(const UINT8 *source, int width, int height, UINT8 *dest, UINT32 &complength)
{
	// set up the output; first byte is 0x80 to indicate lossless encoding
	bitstream_out bitbuf(dest, width * height * 2);
	bitbuf.write(0x80, 8);

	// compute the histograms for the data
	UINT16 *yrle = m_ycontext.rle_and_histo_bitmap(source + 0, width, 2, height);
	UINT16 *cbrle = m_cbcontext.rle_and_histo_bitmap(source + 1, width / 2, 4, height);
	UINT16 *crrle = m_crcontext.rle_and_histo_bitmap(source + 3, width / 2, 4, height);

	// export the trees to the data stream
	huffman_error hufferr = m_ycontext.export_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;
	bitbuf.flush();
	hufferr = m_cbcontext.export_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;
	bitbuf.flush();
	hufferr = m_crcontext.export_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_COMPRESSION_ERROR;
	bitbuf.flush();

	// encode the data using the trees
	for (UINT32 sy = 0; sy < height; sy++)
	{
		m_ycontext.flush_rle();
		m_cbcontext.flush_rle();
		m_crcontext.flush_rle();
		for (UINT32 sx = 0; sx < width / 2; sx++)
		{
			m_ycontext.encode_one(bitbuf, yrle);
			m_cbcontext.encode_one(bitbuf, cbrle);
			m_ycontext.encode_one(bitbuf, yrle);
			m_crcontext.encode_one(bitbuf, crrle);
		}
	}

	// set the final length
	complength = bitbuf.flush();
	return AVHERR_NONE;
}



//**************************************************************************
//  DELTA-RLE ENCODER
//**************************************************************************

//-------------------------------------------------
//  rle_and_histo_bitmap - RLE compress and
//  histogram a bitmap's worth of data
//-------------------------------------------------

UINT16 *avhuff_encoder::deltarle_encoder::rle_and_histo_bitmap(const UINT8 *source, UINT32 items_per_row, UINT32 item_advance, UINT32 row_count)
{
	// resize our RLE buffer
	m_rlebuffer.resize(items_per_row * row_count);
	UINT16 *dest = m_rlebuffer;

	// iterate over rows
	m_encoder.histo_reset();
	UINT8 prevdata = 0;
	for (UINT32 row = 0; row < row_count; row++)
	{
		const UINT8 *end = source + items_per_row * item_advance;
		for ( ; source < end; source += item_advance)
		{
			// fetch current data
			UINT8 curdelta = *source - prevdata;
			prevdata = *source;

			// 0 deltas scan forward for a count
			if (curdelta == 0)
			{
				int zerocount = 1;

				// count the number of consecutive values
				const UINT8 *scandata;
				for (scandata = source + item_advance; scandata < end; scandata += item_advance)
					if (*scandata == prevdata)
						zerocount++;
					else
						break;

				// if we hit the end of a row, maximize the count
				if (scandata >= end && zerocount >= 8)
					zerocount = 100000;

				// encode the maximal count we can
				int rlecode = rlecount_to_code(zerocount);
				m_encoder.histo_one(*dest++ = rlecode);

				// advance past the run
				source += (code_to_rlecount(rlecode) - 1) * item_advance;
			}

			// otherwise, encode the actual data
			else
				m_encoder.histo_one(*dest++ = curdelta);
		}

		// advance to the next row
		source = end;
	}

	// compute the tree for our histogram
	m_encoder.compute_tree_from_histo();
	return m_rlebuffer;
}



//**************************************************************************
//  AVHUFF DECODER
//**************************************************************************

//-------------------------------------------------
//  avhuff_decoder - constructor
//-------------------------------------------------

avhuff_decoder::avhuff_decoder()
{
}


//-------------------------------------------------
//  configure - configure decompression parameters
//-------------------------------------------------

void avhuff_decoder::configure(const avhuff_decompress_config &config)
{
	m_config.video.wrap(config.video, config.video.cliprect());
	m_config.maxsamples = config.maxsamples;
	m_config.actsamples = config.actsamples;
	memcpy(m_config.audio, config.audio, sizeof(m_config.audio));
	m_config.maxmetalength = config.maxmetalength;
	m_config.actmetalength = config.actmetalength;
	m_config.metadata = config.metadata;
}


//-------------------------------------------------
//  decode_data - decode both audio and video from
//  a raw data stream
//-------------------------------------------------

avhuff_error avhuff_decoder::decode_data(const UINT8 *source, UINT32 complength, UINT8 *dest)
{
	// extract info from the header
	if (complength < 8)
		return AVHERR_INVALID_DATA;
	UINT32 metasize = source[0];
	UINT32 channels = source[1];
	UINT32 samples = (source[2] << 8) + source[3];
	UINT32 width = (source[4] << 8) + source[5];
	UINT32 height = (source[6] << 8) + source[7];

	// validate that the sizes make sense
	if (complength < 10 + 2 * channels)
		return AVHERR_INVALID_DATA;
	UINT32 totalsize = 10 + 2 * channels;
	totalsize += (source[8] << 8) | source[9];
	for (int chnum = 0; chnum < channels; chnum++)
		totalsize += (source[10 + 2 * chnum] << 8) | source[11 + 2 * chnum];
	if (totalsize >= complength)
		return AVHERR_INVALID_DATA;

	// starting offsets
	UINT32 srcoffs = 10 + 2 * channels;

	// if we are decoding raw, set up the output parameters
	UINT8 *metastart, *videostart, *audiostart[16];
	UINT32 audioxor, videoxor, videostride;
	if (dest != NULL)
	{
		// create a header
		dest[0] = 'c';
		dest[1] = 'h';
		dest[2] = 'a';
		dest[3] = 'v';
		dest[4] = metasize;
		dest[5] = channels;
		dest[6] = samples >> 8;
		dest[7] = samples;
		dest[8] = width >> 8;
		dest[9] = width;
		dest[10] = height >> 8;
		dest[11] = height;
		dest += 12;

		// determine the start of each piece of data
		metastart = dest;
		dest += metasize;
		for (int chnum = 0; chnum < channels; chnum++)
		{
			audiostart[chnum] = dest;
			dest += 2 * samples;
		}
		videostart = dest;

		// data is assumed to be big-endian already
		audioxor = videoxor = 0;
		videostride = 2 * width;
	}

	// otherwise, extract from the state
	else
	{
		// determine the start of each piece of data
		metastart = m_config.metadata;
		for (int chnum = 0; chnum < channels; chnum++)
			audiostart[chnum] = (UINT8 *)m_config.audio[chnum];
		videostart = (m_config.video.valid()) ? reinterpret_cast<UINT8 *>(&m_config.video.pix(0)) : NULL;
		videostride = (m_config.video.valid()) ? m_config.video.rowpixels() * 2 : 0;

		// data is assumed to be native-endian
		UINT16 betest = 0;
		*(UINT8 *)&betest = 1;
		audioxor = videoxor = (betest == 1) ? 1 : 0;

		// verify against sizes
		if (m_config.video.valid() && (m_config.video.width() < width || m_config.video.height() < height))
			return AVHERR_VIDEO_TOO_LARGE;
		for (int chnum = 0; chnum < channels; chnum++)
			if (m_config.audio[chnum] != NULL && m_config.maxsamples < samples)
				return AVHERR_AUDIO_TOO_LARGE;
		if (m_config.metadata != NULL && m_config.maxmetalength < metasize)
			return AVHERR_METADATA_TOO_LARGE;

		// set the output values
		if (m_config.actsamples != NULL)
			*m_config.actsamples = samples;
		if (m_config.actmetalength != NULL)
			*m_config.actmetalength = metasize;
	}

	// copy the metadata first
	if (metasize > 0)
	{
		if (metastart != NULL)
			memcpy(metastart, source + srcoffs, metasize);
		srcoffs += metasize;
	}

	// decode the audio channels
	if (channels > 0)
	{
		// decode the audio
		avhuff_error err = decode_audio(channels, samples, source + srcoffs, audiostart, audioxor, &source[8]);
		if (err != AVHERR_NONE)
			return err;

		// advance the pointers past the data
		UINT32 treesize = (source[8] << 8) + source[9];
		if (treesize != 0xffff)
			srcoffs += treesize;
		for (int chnum = 0; chnum < channels; chnum++)
			srcoffs += (source[10 + 2 * chnum] << 8) + source[11 + 2 * chnum];
	}

	// decode the video data
	if (width > 0 && height > 0 && videostart != NULL)
	{
		// decode the video
		avhuff_error err = decode_video(width, height, source + srcoffs, complength - srcoffs, videostart, videostride, videoxor);
		if (err != AVHERR_NONE)
			return err;
	}
	return AVHERR_NONE;
}


//-------------------------------------------------
//  decode_audio - decode audio from a compressed
//  data stream
//-------------------------------------------------

avhuff_error avhuff_decoder::decode_audio(int channels, int samples, const UINT8 *source, UINT8 **dest, UINT32 dxor, const UINT8 *sizes)
{
	// extract the huffman trees
	UINT16 treesize = (sizes[0] << 8) | sizes[1];

#if AVHUFF_USE_FLAC

	// if the tree size is 0xffff, the streams are FLAC-encoded
	if (treesize == 0xffff)
	{
		// output data is big-endian; determine our platform endianness
		UINT16 be_test = 0;
		*(UINT8 *)&be_test = 1;
		bool swap_endian = (be_test == 1);
		if (dxor != 0)
			swap_endian = !swap_endian;

		// loop over channels
		for (int chnum = 0; chnum < channels; chnum++)
		{
			// extract the size of this channel
			UINT16 size = (sizes[chnum * 2 + 2] << 8) | sizes[chnum * 2 + 3];

			// only process if the data is requested
			UINT8 *curdest = dest[chnum];
			if (curdest != NULL)
			{
				// reset and decode
				if (!m_flac_decoder.reset(48000, 1, samples, source, size))
					throw CHDERR_DECOMPRESSION_ERROR;
				if (!m_flac_decoder.decode_interleaved(reinterpret_cast<INT16 *>(curdest), samples, swap_endian))
					throw CHDERR_DECOMPRESSION_ERROR;

				// finish up
				m_flac_decoder.finish();
			}

			// advance to the next channel's data
			source += size;
		}
		return AVHERR_NONE;
	}

#endif

	// if we have a non-zero tree size, extract the trees
	if (treesize != 0)
	{
		bitstream_in bitbuf(source, treesize);
		huffman_error hufferr = m_audiohi_decoder.import_tree_rle(bitbuf);
		if (hufferr != HUFFERR_NONE)
			return AVHERR_INVALID_DATA;
		bitbuf.flush();
		hufferr = m_audiolo_decoder.import_tree_rle(bitbuf);
		if (hufferr != HUFFERR_NONE)
			return AVHERR_INVALID_DATA;
		if (bitbuf.flush() != treesize)
			return AVHERR_INVALID_DATA;
		source += treesize;
	}

	// loop over channels
	for (int chnum = 0; chnum < channels; chnum++)
	{
		// extract the size of this channel
		UINT16 size = (sizes[chnum * 2 + 2] << 8) | sizes[chnum * 2 + 3];

		// only process if the data is requested
		UINT8 *curdest = dest[chnum];
		if (curdest != NULL)
		{
			INT16 prevsample = 0;

			// if no huffman length, just copy the data
			if (treesize == 0)
			{
				const UINT8 *cursource = source;
				for (int sampnum = 0; sampnum < samples; sampnum++)
				{
					INT16 delta = (cursource[0] << 8) | cursource[1];
					cursource += 2;

					INT16 newsample = prevsample + delta;
					prevsample = newsample;

					curdest[0 ^ dxor] = newsample >> 8;
					curdest[1 ^ dxor] = newsample;
					curdest += 2;
				}
			}

			// otherwise, Huffman-decode the data
			else
			{
				bitstream_in bitbuf(source, size);
				for (int sampnum = 0; sampnum < samples; sampnum++)
				{
					INT16 delta = m_audiohi_decoder.decode_one(bitbuf) << 8;
					delta |= m_audiolo_decoder.decode_one(bitbuf);

					INT16 newsample = prevsample + delta;
					prevsample = newsample;

					curdest[0 ^ dxor] = newsample >> 8;
					curdest[1 ^ dxor] = newsample;
					curdest += 2;
				}
				if (bitbuf.overflow())
					return AVHERR_INVALID_DATA;
			}
		}

		// advance to the next channel's data
		source += size;
	}
	return AVHERR_NONE;
}


//-------------------------------------------------
//  decode_video - decode video from a compressed
//  data stream
//-------------------------------------------------

avhuff_error avhuff_decoder::decode_video(int width, int height, const UINT8 *source, UINT32 complength, UINT8 *dest, UINT32 dstride, UINT32 dxor)
{
	// if the high bit of the first byte is set, we decode losslessly
	if (source[0] & 0x80)
		return decode_video_lossless(width, height, source, complength, dest, dstride, dxor);
	else
		return AVHERR_INVALID_DATA;
}


//-------------------------------------------------
//  decode_video_lossless - do a lossless video
//  decoding using deltas and huffman encoding
//-------------------------------------------------

avhuff_error avhuff_decoder::decode_video_lossless(int width, int height, const UINT8 *source, UINT32 complength, UINT8 *dest, UINT32 dstride, UINT32 dxor)
{
	// skip the first byte
	bitstream_in bitbuf(source, complength);
	bitbuf.read(8);

	// import the tables
	huffman_error hufferr = m_ycontext.import_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_INVALID_DATA;
	bitbuf.flush();
	hufferr = m_cbcontext.import_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_INVALID_DATA;
	bitbuf.flush();
	hufferr = m_crcontext.import_tree_rle(bitbuf);
	if (hufferr != HUFFERR_NONE)
		return AVHERR_INVALID_DATA;
	bitbuf.flush();

	// decode to the destination
	m_ycontext.reset();
	m_cbcontext.reset();
	m_crcontext.reset();
	for (UINT32 dy = 0; dy < height; dy++)
	{
		UINT8 *row = dest + dy * dstride;
		for (UINT32 dx = 0; dx < width / 2; dx++)
		{
			row[0 ^ dxor] = m_ycontext.decode_one(bitbuf);
			row[1 ^ dxor] = m_cbcontext.decode_one(bitbuf);
			row[2 ^ dxor] = m_ycontext.decode_one(bitbuf);
			row[3 ^ dxor] = m_crcontext.decode_one(bitbuf);
			row += 4;
		}
		m_ycontext.flush_rle();
		m_cbcontext.flush_rle();
		m_crcontext.flush_rle();
	}

	// check for errors if we overflowed or decoded too little data
	if (bitbuf.overflow() || bitbuf.flush() != complength)
		return AVHERR_INVALID_DATA;
	return AVHERR_NONE;
}
