libavcodec/mlp_parser.c - vendor/opensource/ffmpeg - Git at Google

 /*
  * MLP parser
  * Copyright (c) 2007 Ian Caulfield
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 /**
  * @file libavcodec/mlp_parser.c
  * MLP parser
  */

 #include <stdint.h>

 #include "libavutil/crc.h"
 #include "bitstream.h"
 #include "parser.h"
 #include "mlp_parser.h"
 #include "mlp.h"

 static const uint8_t mlp_quants[16] = {
     16, 20, 24, 0, 0, 0, 0, 0,
      0,  0,  0, 0, 0, 0, 0, 0,
 };

 static const uint8_t mlp_channels[32] = {
     1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
     5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 };

 static const uint8_t thd_chancount[13] = {
 //  LR    C   LFE  LRs LRvh  LRc LRrs  Cs   Ts  LRsd  LRw  Cvh  LFE2
      2,   1,   1,   2,   2,   2,   2,   1,   1,   2,   2,   1,   1
 };

 static int mlp_samplerate(int in)
 {
     if (in == 0xF)
         return 0;

     return (in & 8 ? 44100 : 48000) << (in & 7) ;
 }

 static int truehd_channels(int chanmap)
 {
     int channels = 0, i;

     for (i = 0; i < 13; i++)
         channels += thd_chancount[i] * ((chanmap >> i) & 1);

     return channels;
 }

 /** Read a major sync info header - contains high level information about
  *  the stream - sample rate, channel arrangement etc. Most of this
  *  information is not actually necessary for decoding, only for playback.
  *  gb must be a freshly initialized GetBitContext with no bits read.
  */

 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
 {
     int ratebits;
     uint16_t checksum;

     assert(get_bits_count(gb) == 0);

     if (gb->size_in_bits < 28 << 3) {
         av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
         return -1;
     }

     checksum = ff_mlp_checksum16(gb->buffer, 26);
     if (checksum != AV_RL16(gb->buffer+26)) {
         av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
         return -1;
     }

     if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
         return -1;

     mh->stream_type = get_bits(gb, 8);

     if (mh->stream_type == 0xbb) {
         mh->group1_bits = mlp_quants[get_bits(gb, 4)];
         mh->group2_bits = mlp_quants[get_bits(gb, 4)];

         ratebits = get_bits(gb, 4);
         mh->group1_samplerate = mlp_samplerate(ratebits);
         mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));

         skip_bits(gb, 11);

         mh->channels_mlp = get_bits(gb, 5);
     } else if (mh->stream_type == 0xba) {
         mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
         mh->group2_bits = 0;

         ratebits = get_bits(gb, 4);
         mh->group1_samplerate = mlp_samplerate(ratebits);
         mh->group2_samplerate = 0;

         skip_bits(gb, 8);

         mh->channels_thd_stream1 = get_bits(gb, 5);

         skip_bits(gb, 2);

         mh->channels_thd_stream2 = get_bits(gb, 13);
     } else
         return -1;

     mh->access_unit_size = 40 << (ratebits & 7);
     mh->access_unit_size_pow2 = 64 << (ratebits & 7);

     skip_bits_long(gb, 48);

     mh->is_vbr = get_bits1(gb);

     mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;

     mh->num_substreams = get_bits(gb, 4);

     skip_bits_long(gb, 4 + 11 * 8);

     return 0;
 }

 typedef struct MLPParseContext
 {
     ParseContext pc;

     int bytes_left;

     int in_sync;

     int num_substreams;
 } MLPParseContext;

 static av_cold int mlp_init(AVCodecParserContext *s)
 {
     ff_mlp_init_crc();
     return 0;
 }

 static int mlp_parse(AVCodecParserContext *s,
                      AVCodecContext *avctx,
                      const uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size)
 {
     MLPParseContext *mp = s->priv_data;
     int sync_present;
     uint8_t parity_bits;
     int next;
     int i, p = 0;

     *poutbuf_size = 0;
     if (buf_size == 0)
         return 0;

     if (!mp->in_sync) {
         // Not in sync - find a major sync header

         for (i = 0; i < buf_size; i++) {
             mp->pc.state = (mp->pc.state << 8) | buf[i];
             if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
                 mp->in_sync = 1;
                 mp->bytes_left = 0;
                 break;
             }
         }

         if (!mp->in_sync) {
             ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
             return buf_size;
         }

         ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);

         return i - 7;
     }

     if (mp->bytes_left == 0) {
         // Find length of this packet

         /* Copy overread bytes from last frame into buffer. */
         for(; mp->pc.overread>0; mp->pc.overread--) {
             mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
         }

         if (mp->pc.index + buf_size < 2) {
             ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
             return buf_size;
         }

         mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
                        |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
         mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
         mp->bytes_left -= mp->pc.index;
     }

     next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;

     if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
         mp->bytes_left -= buf_size;
         return buf_size;
     }

     mp->bytes_left = 0;

     sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;

     if (!sync_present) {
         /* The first nibble of a frame is a parity check of the 4-byte
          * access unit header and all the 2- or 4-byte substream headers. */
         // Only check when this isn't a sync frame - syncs have a checksum.

         parity_bits = 0;
         for (i = -1; i < mp->num_substreams; i++) {
             parity_bits ^= buf[p++];
             parity_bits ^= buf[p++];

             if (i < 0 || buf[p-2] & 0x80) {
                 parity_bits ^= buf[p++];
                 parity_bits ^= buf[p++];
             }
         }

         if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
             av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
             goto lost_sync;
         }
     } else {
         GetBitContext gb;
         MLPHeaderInfo mh;

         init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
         if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
             goto lost_sync;

         avctx->bits_per_raw_sample = mh.group1_bits;
         if (avctx->bits_per_raw_sample > 16)
             avctx->sample_fmt = SAMPLE_FMT_S32;
         else
             avctx->sample_fmt = SAMPLE_FMT_S16;
         avctx->sample_rate = mh.group1_samplerate;
         avctx->frame_size = mh.access_unit_size;

         if (mh.stream_type == 0xbb) {
             /* MLP stream */
             avctx->channels = mlp_channels[mh.channels_mlp];
         } else { /* mh.stream_type == 0xba */
             /* TrueHD stream */
             if (mh.channels_thd_stream2)
                 avctx->channels = truehd_channels(mh.channels_thd_stream2);
             else
                 avctx->channels = truehd_channels(mh.channels_thd_stream1);
         }

         if (!mh.is_vbr) /* Stream is CBR */
             avctx->bit_rate = mh.peak_bitrate;

         mp->num_substreams = mh.num_substreams;
     }

     *poutbuf = buf;
     *poutbuf_size = buf_size;

     return next;

 lost_sync:
     mp->in_sync = 0;
     return 1;
 }

 AVCodecParser mlp_parser = {
     { CODEC_ID_MLP },
     sizeof(MLPParseContext),
     mlp_init,
     mlp_parse,
     NULL,
 };
	/*
	* MLP parser
	* Copyright (c) 2007 Ian Caulfield
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg 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
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	/**
	* @file libavcodec/mlp_parser.c
	* MLP parser
	*/

	#include <stdint.h>

	#include "libavutil/crc.h"
	#include "bitstream.h"
	#include "parser.h"
	#include "mlp_parser.h"
	#include "mlp.h"

	static const uint8_t mlp_quants[16] = {
	16, 20, 24, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	};

	static const uint8_t mlp_channels[32] = {
	1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
	5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	};

	static const uint8_t thd_chancount[13] = {
	// LR C LFE LRs LRvh LRc LRrs Cs Ts LRsd LRw Cvh LFE2
	2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1
	};

	static int mlp_samplerate(int in)
	{
	if (in == 0xF)
	return 0;

	return (in & 8 ? 44100 : 48000) << (in & 7) ;
	}

	static int truehd_channels(int chanmap)
	{
	int channels = 0, i;

	for (i = 0; i < 13; i++)
	channels += thd_chancount[i] * ((chanmap >> i) & 1);

	return channels;
	}

	/** Read a major sync info header - contains high level information about
	* the stream - sample rate, channel arrangement etc. Most of this
	* information is not actually necessary for decoding, only for playback.
	* gb must be a freshly initialized GetBitContext with no bits read.
	*/

	int ff_mlp_read_major_sync(void log, MLPHeaderInfo mh, GetBitContext *gb)
	{
	int ratebits;
	uint16_t checksum;

	assert(get_bits_count(gb) == 0);

	if (gb->size_in_bits < 28 << 3) {
	av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
	return -1;
	}

	checksum = ff_mlp_checksum16(gb->buffer, 26);
	if (checksum != AV_RL16(gb->buffer+26)) {
	av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
	return -1;
	}

	if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
	return -1;

	mh->stream_type = get_bits(gb, 8);

	if (mh->stream_type == 0xbb) {
	mh->group1_bits = mlp_quants[get_bits(gb, 4)];
	mh->group2_bits = mlp_quants[get_bits(gb, 4)];

	ratebits = get_bits(gb, 4);
	mh->group1_samplerate = mlp_samplerate(ratebits);
	mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));

	skip_bits(gb, 11);

	mh->channels_mlp = get_bits(gb, 5);
	} else if (mh->stream_type == 0xba) {
	mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
	mh->group2_bits = 0;

	ratebits = get_bits(gb, 4);
	mh->group1_samplerate = mlp_samplerate(ratebits);
	mh->group2_samplerate = 0;

	skip_bits(gb, 8);

	mh->channels_thd_stream1 = get_bits(gb, 5);

	skip_bits(gb, 2);

	mh->channels_thd_stream2 = get_bits(gb, 13);
	} else
	return -1;

	mh->access_unit_size = 40 << (ratebits & 7);
	mh->access_unit_size_pow2 = 64 << (ratebits & 7);

	skip_bits_long(gb, 48);

	mh->is_vbr = get_bits1(gb);

	mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;

	mh->num_substreams = get_bits(gb, 4);

	skip_bits_long(gb, 4 + 11 * 8);

	return 0;
	}

	typedef struct MLPParseContext
	{
	ParseContext pc;

	int bytes_left;

	int in_sync;

	int num_substreams;
	} MLPParseContext;

	static av_cold int mlp_init(AVCodecParserContext *s)
	{
	ff_mlp_init_crc();
	return 0;
	}

	static int mlp_parse(AVCodecParserContext *s,
	AVCodecContext *avctx,
	const uint8_t *poutbuf, int poutbuf_size,
	const uint8_t *buf, int buf_size)
	{
	MLPParseContext *mp = s->priv_data;
	int sync_present;
	uint8_t parity_bits;
	int next;
	int i, p = 0;

	*poutbuf_size = 0;
	if (buf_size == 0)
	return 0;

	if (!mp->in_sync) {
	// Not in sync - find a major sync header

	for (i = 0; i < buf_size; i++) {
	mp->pc.state = (mp->pc.state << 8) \| buf[i];
	if ((mp->pc.state & 0xfffffffe) == 0xf8726fba) {
	mp->in_sync = 1;
	mp->bytes_left = 0;
	break;
	}
	}

	if (!mp->in_sync) {
	ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
	return buf_size;
	}

	ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);

	return i - 7;
	}

	if (mp->bytes_left == 0) {
	// Find length of this packet

	/* Copy overread bytes from last frame into buffer. */
	for(; mp->pc.overread>0; mp->pc.overread--) {
	mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
	}

	if (mp->pc.index + buf_size < 2) {
	ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size);
	return buf_size;
	}

	mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
	\| (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
	mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
	mp->bytes_left -= mp->pc.index;
	}

	next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;

	if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
	mp->bytes_left -= buf_size;
	return buf_size;
	}

	mp->bytes_left = 0;

	sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;

	if (!sync_present) {
	/* The first nibble of a frame is a parity check of the 4-byte
	* access unit header and all the 2- or 4-byte substream headers. */
	// Only check when this isn't a sync frame - syncs have a checksum.

	parity_bits = 0;
	for (i = -1; i < mp->num_substreams; i++) {
	parity_bits ^= buf[p++];
	parity_bits ^= buf[p++];

	if (i < 0 \|\| buf[p-2] & 0x80) {
	parity_bits ^= buf[p++];
	parity_bits ^= buf[p++];
	}
	}

	if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
	av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
	goto lost_sync;
	}
	} else {
	GetBitContext gb;
	MLPHeaderInfo mh;

	init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
	if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
	goto lost_sync;

	avctx->bits_per_raw_sample = mh.group1_bits;
	if (avctx->bits_per_raw_sample > 16)
	avctx->sample_fmt = SAMPLE_FMT_S32;
	else
	avctx->sample_fmt = SAMPLE_FMT_S16;
	avctx->sample_rate = mh.group1_samplerate;
	avctx->frame_size = mh.access_unit_size;

	if (mh.stream_type == 0xbb) {
	/* MLP stream */
	avctx->channels = mlp_channels[mh.channels_mlp];
	} else { /* mh.stream_type == 0xba */
	/* TrueHD stream */
	if (mh.channels_thd_stream2)
	avctx->channels = truehd_channels(mh.channels_thd_stream2);
	else
	avctx->channels = truehd_channels(mh.channels_thd_stream1);
	}

	if (!mh.is_vbr) /* Stream is CBR */
	avctx->bit_rate = mh.peak_bitrate;

	mp->num_substreams = mh.num_substreams;
	}

	*poutbuf = buf;
	*poutbuf_size = buf_size;

	return next;

	lost_sync:
	mp->in_sync = 0;
	return 1;
	}

	AVCodecParser mlp_parser = {
	{ CODEC_ID_MLP },
	sizeof(MLPParseContext),
	mlp_init,
	mlp_parse,
	NULL,
	};