libavformat/westwood.c - vendor/opensource/ffmpeg - Git at Google

 /*
  * Westwood Studios Multimedia Formats Demuxer (VQA, AUD)
  * Copyright (c) 2003 The ffmpeg Project
  *
  * 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 libavformat/westwood.c
  * Westwood Studios VQA & AUD file demuxers
  * by Mike Melanson (melanson@pcisys.net)
  * for more information on the Westwood file formats, visit:
  *   http://www.pcisys.net/~melanson/codecs/
  *   http://www.geocities.com/SiliconValley/8682/aud3.txt
  *
  * Implementation note: There is no definite file signature for AUD files.
  * The demuxer uses a probabilistic strategy for content detection. This
  * entails performing sanity checks on certain header values in order to
  * qualify a file. Refer to wsaud_probe() for the precise parameters.
  */

 #include "libavutil/intreadwrite.h"
 #include "avformat.h"

 #define AUD_HEADER_SIZE 12
 #define AUD_CHUNK_PREAMBLE_SIZE 8
 #define AUD_CHUNK_SIGNATURE 0x0000DEAF

 #define FORM_TAG MKBETAG('F', 'O', 'R', 'M')
 #define WVQA_TAG MKBETAG('W', 'V', 'Q', 'A')
 #define VQHD_TAG MKBETAG('V', 'Q', 'H', 'D')
 #define FINF_TAG MKBETAG('F', 'I', 'N', 'F')
 #define SND0_TAG MKBETAG('S', 'N', 'D', '0')
 #define SND1_TAG MKBETAG('S', 'N', 'D', '1')
 #define SND2_TAG MKBETAG('S', 'N', 'D', '2')
 #define VQFR_TAG MKBETAG('V', 'Q', 'F', 'R')

 /* don't know what these tags are for, but acknowledge their existence */
 #define CINF_TAG MKBETAG('C', 'I', 'N', 'F')
 #define CINH_TAG MKBETAG('C', 'I', 'N', 'H')
 #define CIND_TAG MKBETAG('C', 'I', 'N', 'D')
 #define PINF_TAG MKBETAG('P', 'I', 'N', 'F')
 #define PINH_TAG MKBETAG('P', 'I', 'N', 'H')
 #define PIND_TAG MKBETAG('P', 'I', 'N', 'D')
 #define CMDS_TAG MKBETAG('C', 'M', 'D', 'S')

 #define VQA_HEADER_SIZE 0x2A
 #define VQA_FRAMERATE 15
 #define VQA_VIDEO_PTS_INC (90000 / VQA_FRAMERATE)
 #define VQA_PREAMBLE_SIZE 8

 typedef struct WsAudDemuxContext {
     int audio_samplerate;
     int audio_channels;
     int audio_bits;
     enum CodecID audio_type;
     int audio_stream_index;
     int64_t audio_frame_counter;
 } WsAudDemuxContext;

 typedef struct WsVqaDemuxContext {
     int audio_samplerate;
     int audio_channels;
     int audio_bits;

     int audio_stream_index;
     int video_stream_index;

     int64_t audio_frame_counter;
     int64_t video_pts;
 } WsVqaDemuxContext;

 static int wsaud_probe(AVProbeData *p)
 {
     int field;

     /* Probabilistic content detection strategy: There is no file signature
      * so perform sanity checks on various header parameters:
      *   8000 <= sample rate (16 bits) <= 48000  ==> 40001 acceptable numbers
      *   flags <= 0x03 (2 LSBs are used)         ==> 4 acceptable numbers
      *   compression type (8 bits) = 1 or 99     ==> 2 acceptable numbers
      *   first audio chunk signature (32 bits)   ==> 1 acceptable number
      * The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 =
      * 320008 acceptable number combinations.
      */

     if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE)
         return 0;

     /* check sample rate */
     field = AV_RL16(&p->buf[0]);
     if ((field < 8000) || (field > 48000))
         return 0;

     /* enforce the rule that the top 6 bits of this flags field are reserved (0);
      * this might not be true, but enforce it until deemed unnecessary */
     if (p->buf[10] & 0xFC)
         return 0;

     /* note: only check for WS IMA (type 99) right now since there is no
      * support for type 1 */
     if (p->buf[11] != 99)
         return 0;

     /* read ahead to the first audio chunk and validate the first header signature */
     if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
         return 0;

     /* return 1/2 certainty since this file check is a little sketchy */
     return AVPROBE_SCORE_MAX / 2;
 }

 static int wsaud_read_header(AVFormatContext *s,
                              AVFormatParameters *ap)
 {
     WsAudDemuxContext *wsaud = s->priv_data;
     ByteIOContext *pb = s->pb;
     AVStream *st;
     unsigned char header[AUD_HEADER_SIZE];

     if (get_buffer(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE)
         return AVERROR(EIO);
     wsaud->audio_samplerate = AV_RL16(&header[0]);
     if (header[11] == 99)
         wsaud->audio_type = CODEC_ID_ADPCM_IMA_WS;
     else
         return AVERROR_INVALIDDATA;

     /* flag 0 indicates stereo */
     wsaud->audio_channels = (header[10] & 0x1) + 1;
     /* flag 1 indicates 16 bit audio */
     wsaud->audio_bits = (((header[10] & 0x2) >> 1) + 1) * 8;

     /* initialize the audio decoder stream */
     st = av_new_stream(s, 0);
     if (!st)
         return AVERROR(ENOMEM);
     av_set_pts_info(st, 33, 1, wsaud->audio_samplerate);
     st->codec->codec_type = CODEC_TYPE_AUDIO;
     st->codec->codec_id = wsaud->audio_type;
     st->codec->codec_tag = 0;  /* no tag */
     st->codec->channels = wsaud->audio_channels;
     st->codec->sample_rate = wsaud->audio_samplerate;
     st->codec->bits_per_coded_sample = wsaud->audio_bits;
     st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
         st->codec->bits_per_coded_sample / 4;
     st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;

     wsaud->audio_stream_index = st->index;
     wsaud->audio_frame_counter = 0;

     return 0;
 }

 static int wsaud_read_packet(AVFormatContext *s,
                              AVPacket *pkt)
 {
     WsAudDemuxContext *wsaud = s->priv_data;
     ByteIOContext *pb = s->pb;
     unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
     unsigned int chunk_size;
     int ret = 0;

     if (get_buffer(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
         AUD_CHUNK_PREAMBLE_SIZE)
         return AVERROR(EIO);

     /* validate the chunk */
     if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
         return AVERROR_INVALIDDATA;

     chunk_size = AV_RL16(&preamble[0]);
     ret= av_get_packet(pb, pkt, chunk_size);
     if (ret != chunk_size)
         return AVERROR(EIO);
     pkt->stream_index = wsaud->audio_stream_index;
     pkt->pts = wsaud->audio_frame_counter;
     pkt->pts /= wsaud->audio_samplerate;

     /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
     wsaud->audio_frame_counter += (chunk_size * 2) / wsaud->audio_channels;

     return ret;
 }

 static int wsvqa_probe(AVProbeData *p)
 {
     /* need 12 bytes to qualify */
     if (p->buf_size < 12)
         return 0;

     /* check for the VQA signatures */
     if ((AV_RB32(&p->buf[0]) != FORM_TAG) ||
         (AV_RB32(&p->buf[8]) != WVQA_TAG))
         return 0;

     return AVPROBE_SCORE_MAX;
 }

 static int wsvqa_read_header(AVFormatContext *s,
                              AVFormatParameters *ap)
 {
     WsVqaDemuxContext *wsvqa = s->priv_data;
     ByteIOContext *pb = s->pb;
     AVStream *st;
     unsigned char *header;
     unsigned char scratch[VQA_PREAMBLE_SIZE];
     unsigned int chunk_tag;
     unsigned int chunk_size;

     /* initialize the video decoder stream */
     st = av_new_stream(s, 0);
     if (!st)
         return AVERROR(ENOMEM);
     av_set_pts_info(st, 33, 1, VQA_FRAMERATE);
     wsvqa->video_stream_index = st->index;
     st->codec->codec_type = CODEC_TYPE_VIDEO;
     st->codec->codec_id = CODEC_ID_WS_VQA;
     st->codec->codec_tag = 0;  /* no fourcc */

     /* skip to the start of the VQA header */
     url_fseek(pb, 20, SEEK_SET);

     /* the VQA header needs to go to the decoder */
     st->codec->extradata_size = VQA_HEADER_SIZE;
     st->codec->extradata = av_mallocz(VQA_HEADER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
     header = (unsigned char *)st->codec->extradata;
     if (get_buffer(pb, st->codec->extradata, VQA_HEADER_SIZE) !=
         VQA_HEADER_SIZE) {
         av_free(st->codec->extradata);
         return AVERROR(EIO);
     }
     st->codec->width = AV_RL16(&header[6]);
     st->codec->height = AV_RL16(&header[8]);

     /* initialize the audio decoder stream for VQA v1 or nonzero samplerate */
     if (AV_RL16(&header[24]) || (AV_RL16(&header[0]) == 1 && AV_RL16(&header[2]) == 1)) {
         st = av_new_stream(s, 0);
         if (!st)
             return AVERROR(ENOMEM);
         av_set_pts_info(st, 33, 1, VQA_FRAMERATE);
         st->codec->codec_type = CODEC_TYPE_AUDIO;
         if (AV_RL16(&header[0]) == 1)
             st->codec->codec_id = CODEC_ID_WESTWOOD_SND1;
         else
             st->codec->codec_id = CODEC_ID_ADPCM_IMA_WS;
         st->codec->codec_tag = 0;  /* no tag */
         st->codec->sample_rate = AV_RL16(&header[24]);
         if (!st->codec->sample_rate)
             st->codec->sample_rate = 22050;
         st->codec->channels = header[26];
         if (!st->codec->channels)
             st->codec->channels = 1;
         st->codec->bits_per_coded_sample = 16;
         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
             st->codec->bits_per_coded_sample / 4;
         st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;

         wsvqa->audio_stream_index = st->index;
         wsvqa->audio_samplerate = st->codec->sample_rate;
         wsvqa->audio_channels = st->codec->channels;
         wsvqa->audio_frame_counter = 0;
     }

     /* there are 0 or more chunks before the FINF chunk; iterate until
      * FINF has been skipped and the file will be ready to be demuxed */
     do {
         if (get_buffer(pb, scratch, VQA_PREAMBLE_SIZE) != VQA_PREAMBLE_SIZE)
             return AVERROR(EIO);
         chunk_tag = AV_RB32(&scratch[0]);
         chunk_size = AV_RB32(&scratch[4]);

         /* catch any unknown header tags, for curiousity */
         switch (chunk_tag) {
         case CINF_TAG:
         case CINH_TAG:
         case CIND_TAG:
         case PINF_TAG:
         case PINH_TAG:
         case PIND_TAG:
         case FINF_TAG:
         case CMDS_TAG:
             break;

         default:
             av_log (s, AV_LOG_ERROR, " note: unknown chunk seen (%c%c%c%c)\n",
                 scratch[0], scratch[1],
                 scratch[2], scratch[3]);
             break;
         }

         url_fseek(pb, chunk_size, SEEK_CUR);
     } while (chunk_tag != FINF_TAG);

     wsvqa->video_pts = wsvqa->audio_frame_counter = 0;

     return 0;
 }

 static int wsvqa_read_packet(AVFormatContext *s,
                              AVPacket *pkt)
 {
     WsVqaDemuxContext *wsvqa = s->priv_data;
     ByteIOContext *pb = s->pb;
     int ret = -1;
     unsigned char preamble[VQA_PREAMBLE_SIZE];
     unsigned int chunk_type;
     unsigned int chunk_size;
     int skip_byte;

     while (get_buffer(pb, preamble, VQA_PREAMBLE_SIZE) == VQA_PREAMBLE_SIZE) {
         chunk_type = AV_RB32(&preamble[0]);
         chunk_size = AV_RB32(&preamble[4]);
         skip_byte = chunk_size & 0x01;

         if ((chunk_type == SND1_TAG) || (chunk_type == SND2_TAG) || (chunk_type == VQFR_TAG)) {

             if (av_new_packet(pkt, chunk_size))
                 return AVERROR(EIO);
             ret = get_buffer(pb, pkt->data, chunk_size);
             if (ret != chunk_size) {
                 av_free_packet(pkt);
                 return AVERROR(EIO);
             }

             if (chunk_type == SND2_TAG) {
                 pkt->stream_index = wsvqa->audio_stream_index;
                 /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
                 wsvqa->audio_frame_counter += (chunk_size * 2) / wsvqa->audio_channels;
             } else if(chunk_type == SND1_TAG) {
                 pkt->stream_index = wsvqa->audio_stream_index;
                 /* unpacked size is stored in header */
                 wsvqa->audio_frame_counter += AV_RL16(pkt->data) / wsvqa->audio_channels;
             } else {
                 pkt->stream_index = wsvqa->video_stream_index;
                 wsvqa->video_pts += VQA_VIDEO_PTS_INC;
             }
             /* stay on 16-bit alignment */
             if (skip_byte)
                 url_fseek(pb, 1, SEEK_CUR);

             return ret;
         } else {
             switch(chunk_type){
             case CMDS_TAG:
             case SND0_TAG:
                 break;
             default:
                 av_log(s, AV_LOG_INFO, "Skipping unknown chunk 0x%08X\n", chunk_type);
             }
             url_fseek(pb, chunk_size + skip_byte, SEEK_CUR);
         }
     }

     return ret;
 }

 #if CONFIG_WSAUD_DEMUXER
 AVInputFormat wsaud_demuxer = {
     "wsaud",
     NULL_IF_CONFIG_SMALL("Westwood Studios audio format"),
     sizeof(WsAudDemuxContext),
     wsaud_probe,
     wsaud_read_header,
     wsaud_read_packet,
 };
 #endif
 #if CONFIG_WSVQA_DEMUXER
 AVInputFormat wsvqa_demuxer = {
     "wsvqa",
     NULL_IF_CONFIG_SMALL("Westwood Studios VQA format"),
     sizeof(WsVqaDemuxContext),
     wsvqa_probe,
     wsvqa_read_header,
     wsvqa_read_packet,
 };
 #endif
	/*
	* Westwood Studios Multimedia Formats Demuxer (VQA, AUD)
	* Copyright (c) 2003 The ffmpeg Project
	*
	* 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 libavformat/westwood.c
	* Westwood Studios VQA & AUD file demuxers
	* by Mike Melanson (melanson@pcisys.net)
	* for more information on the Westwood file formats, visit:
	* http://www.pcisys.net/~melanson/codecs/
	* http://www.geocities.com/SiliconValley/8682/aud3.txt
	*
	* Implementation note: There is no definite file signature for AUD files.
	* The demuxer uses a probabilistic strategy for content detection. This
	* entails performing sanity checks on certain header values in order to
	* qualify a file. Refer to wsaud_probe() for the precise parameters.
	*/

	#include "libavutil/intreadwrite.h"
	#include "avformat.h"

	#define AUD_HEADER_SIZE 12
	#define AUD_CHUNK_PREAMBLE_SIZE 8
	#define AUD_CHUNK_SIGNATURE 0x0000DEAF

	#define FORM_TAG MKBETAG('F', 'O', 'R', 'M')
	#define WVQA_TAG MKBETAG('W', 'V', 'Q', 'A')
	#define VQHD_TAG MKBETAG('V', 'Q', 'H', 'D')
	#define FINF_TAG MKBETAG('F', 'I', 'N', 'F')
	#define SND0_TAG MKBETAG('S', 'N', 'D', '0')
	#define SND1_TAG MKBETAG('S', 'N', 'D', '1')
	#define SND2_TAG MKBETAG('S', 'N', 'D', '2')
	#define VQFR_TAG MKBETAG('V', 'Q', 'F', 'R')

	/* don't know what these tags are for, but acknowledge their existence */
	#define CINF_TAG MKBETAG('C', 'I', 'N', 'F')
	#define CINH_TAG MKBETAG('C', 'I', 'N', 'H')
	#define CIND_TAG MKBETAG('C', 'I', 'N', 'D')
	#define PINF_TAG MKBETAG('P', 'I', 'N', 'F')
	#define PINH_TAG MKBETAG('P', 'I', 'N', 'H')
	#define PIND_TAG MKBETAG('P', 'I', 'N', 'D')
	#define CMDS_TAG MKBETAG('C', 'M', 'D', 'S')

	#define VQA_HEADER_SIZE 0x2A
	#define VQA_FRAMERATE 15
	#define VQA_VIDEO_PTS_INC (90000 / VQA_FRAMERATE)
	#define VQA_PREAMBLE_SIZE 8

	typedef struct WsAudDemuxContext {
	int audio_samplerate;
	int audio_channels;
	int audio_bits;
	enum CodecID audio_type;
	int audio_stream_index;
	int64_t audio_frame_counter;
	} WsAudDemuxContext;

	typedef struct WsVqaDemuxContext {
	int audio_samplerate;
	int audio_channels;
	int audio_bits;

	int audio_stream_index;
	int video_stream_index;

	int64_t audio_frame_counter;
	int64_t video_pts;
	} WsVqaDemuxContext;

	static int wsaud_probe(AVProbeData *p)
	{
	int field;

	/* Probabilistic content detection strategy: There is no file signature
	* so perform sanity checks on various header parameters:
	* 8000 <= sample rate (16 bits) <= 48000 ==> 40001 acceptable numbers
	* flags <= 0x03 (2 LSBs are used) ==> 4 acceptable numbers
	* compression type (8 bits) = 1 or 99 ==> 2 acceptable numbers
	* first audio chunk signature (32 bits) ==> 1 acceptable number
	* The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 =
	* 320008 acceptable number combinations.
	*/

	if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE)
	return 0;

	/* check sample rate */
	field = AV_RL16(&p->buf[0]);
	if ((field < 8000) \|\| (field > 48000))
	return 0;

	/* enforce the rule that the top 6 bits of this flags field are reserved (0);
	* this might not be true, but enforce it until deemed unnecessary */
	if (p->buf[10] & 0xFC)
	return 0;

	/* note: only check for WS IMA (type 99) right now since there is no
	* support for type 1 */
	if (p->buf[11] != 99)
	return 0;

	/* read ahead to the first audio chunk and validate the first header signature */
	if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
	return 0;

	/* return 1/2 certainty since this file check is a little sketchy */
	return AVPROBE_SCORE_MAX / 2;
	}

	static int wsaud_read_header(AVFormatContext *s,
	AVFormatParameters *ap)
	{
	WsAudDemuxContext *wsaud = s->priv_data;
	ByteIOContext *pb = s->pb;
	AVStream *st;
	unsigned char header[AUD_HEADER_SIZE];

	if (get_buffer(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE)
	return AVERROR(EIO);
	wsaud->audio_samplerate = AV_RL16(&header[0]);
	if (header[11] == 99)
	wsaud->audio_type = CODEC_ID_ADPCM_IMA_WS;
	else
	return AVERROR_INVALIDDATA;

	/* flag 0 indicates stereo */
	wsaud->audio_channels = (header[10] & 0x1) + 1;
	/* flag 1 indicates 16 bit audio */
	wsaud->audio_bits = (((header[10] & 0x2) >> 1) + 1) * 8;

	/* initialize the audio decoder stream */
	st = av_new_stream(s, 0);
	if (!st)
	return AVERROR(ENOMEM);
	av_set_pts_info(st, 33, 1, wsaud->audio_samplerate);
	st->codec->codec_type = CODEC_TYPE_AUDIO;
	st->codec->codec_id = wsaud->audio_type;
	st->codec->codec_tag = 0; /* no tag */
	st->codec->channels = wsaud->audio_channels;
	st->codec->sample_rate = wsaud->audio_samplerate;
	st->codec->bits_per_coded_sample = wsaud->audio_bits;
	st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
	st->codec->bits_per_coded_sample / 4;
	st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;

	wsaud->audio_stream_index = st->index;
	wsaud->audio_frame_counter = 0;

	return 0;
	}

	static int wsaud_read_packet(AVFormatContext *s,
	AVPacket *pkt)
	{
	WsAudDemuxContext *wsaud = s->priv_data;
	ByteIOContext *pb = s->pb;
	unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
	unsigned int chunk_size;
	int ret = 0;

	if (get_buffer(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
	AUD_CHUNK_PREAMBLE_SIZE)
	return AVERROR(EIO);

	/* validate the chunk */
	if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
	return AVERROR_INVALIDDATA;

	chunk_size = AV_RL16(&preamble[0]);
	ret= av_get_packet(pb, pkt, chunk_size);
	if (ret != chunk_size)
	return AVERROR(EIO);
	pkt->stream_index = wsaud->audio_stream_index;
	pkt->pts = wsaud->audio_frame_counter;
	pkt->pts /= wsaud->audio_samplerate;

	/* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
	wsaud->audio_frame_counter += (chunk_size * 2) / wsaud->audio_channels;

	return ret;
	}

	static int wsvqa_probe(AVProbeData *p)
	{
	/* need 12 bytes to qualify */
	if (p->buf_size < 12)
	return 0;

	/* check for the VQA signatures */
	if ((AV_RB32(&p->buf[0]) != FORM_TAG) \|\|
	(AV_RB32(&p->buf[8]) != WVQA_TAG))
	return 0;

	return AVPROBE_SCORE_MAX;
	}

	static int wsvqa_read_header(AVFormatContext *s,
	AVFormatParameters *ap)
	{
	WsVqaDemuxContext *wsvqa = s->priv_data;
	ByteIOContext *pb = s->pb;
	AVStream *st;
	unsigned char *header;
	unsigned char scratch[VQA_PREAMBLE_SIZE];
	unsigned int chunk_tag;
	unsigned int chunk_size;

	/* initialize the video decoder stream */
	st = av_new_stream(s, 0);
	if (!st)
	return AVERROR(ENOMEM);
	av_set_pts_info(st, 33, 1, VQA_FRAMERATE);
	wsvqa->video_stream_index = st->index;
	st->codec->codec_type = CODEC_TYPE_VIDEO;
	st->codec->codec_id = CODEC_ID_WS_VQA;
	st->codec->codec_tag = 0; /* no fourcc */

	/* skip to the start of the VQA header */
	url_fseek(pb, 20, SEEK_SET);

	/* the VQA header needs to go to the decoder */
	st->codec->extradata_size = VQA_HEADER_SIZE;
	st->codec->extradata = av_mallocz(VQA_HEADER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
	header = (unsigned char *)st->codec->extradata;
	if (get_buffer(pb, st->codec->extradata, VQA_HEADER_SIZE) !=
	VQA_HEADER_SIZE) {
	av_free(st->codec->extradata);
	return AVERROR(EIO);
	}
	st->codec->width = AV_RL16(&header[6]);
	st->codec->height = AV_RL16(&header[8]);

	/* initialize the audio decoder stream for VQA v1 or nonzero samplerate */
	if (AV_RL16(&header[24]) \|\| (AV_RL16(&header[0]) == 1 && AV_RL16(&header[2]) == 1)) {
	st = av_new_stream(s, 0);
	if (!st)
	return AVERROR(ENOMEM);
	av_set_pts_info(st, 33, 1, VQA_FRAMERATE);
	st->codec->codec_type = CODEC_TYPE_AUDIO;
	if (AV_RL16(&header[0]) == 1)
	st->codec->codec_id = CODEC_ID_WESTWOOD_SND1;
	else
	st->codec->codec_id = CODEC_ID_ADPCM_IMA_WS;
	st->codec->codec_tag = 0; /* no tag */
	st->codec->sample_rate = AV_RL16(&header[24]);
	if (!st->codec->sample_rate)
	st->codec->sample_rate = 22050;
	st->codec->channels = header[26];
	if (!st->codec->channels)
	st->codec->channels = 1;
	st->codec->bits_per_coded_sample = 16;
	st->codec->bit_rate = st->codec->channels * st->codec->sample_rate *
	st->codec->bits_per_coded_sample / 4;
	st->codec->block_align = st->codec->channels * st->codec->bits_per_coded_sample;

	wsvqa->audio_stream_index = st->index;
	wsvqa->audio_samplerate = st->codec->sample_rate;
	wsvqa->audio_channels = st->codec->channels;
	wsvqa->audio_frame_counter = 0;
	}

	/* there are 0 or more chunks before the FINF chunk; iterate until
	* FINF has been skipped and the file will be ready to be demuxed */
	do {
	if (get_buffer(pb, scratch, VQA_PREAMBLE_SIZE) != VQA_PREAMBLE_SIZE)
	return AVERROR(EIO);
	chunk_tag = AV_RB32(&scratch[0]);
	chunk_size = AV_RB32(&scratch[4]);

	/* catch any unknown header tags, for curiousity */
	switch (chunk_tag) {
	case CINF_TAG:
	case CINH_TAG:
	case CIND_TAG:
	case PINF_TAG:
	case PINH_TAG:
	case PIND_TAG:
	case FINF_TAG:
	case CMDS_TAG:
	break;

	default:
	av_log (s, AV_LOG_ERROR, " note: unknown chunk seen (%c%c%c%c)\n",
	scratch[0], scratch[1],
	scratch[2], scratch[3]);
	break;
	}

	url_fseek(pb, chunk_size, SEEK_CUR);
	} while (chunk_tag != FINF_TAG);

	wsvqa->video_pts = wsvqa->audio_frame_counter = 0;

	return 0;
	}

	static int wsvqa_read_packet(AVFormatContext *s,
	AVPacket *pkt)
	{
	WsVqaDemuxContext *wsvqa = s->priv_data;
	ByteIOContext *pb = s->pb;
	int ret = -1;
	unsigned char preamble[VQA_PREAMBLE_SIZE];
	unsigned int chunk_type;
	unsigned int chunk_size;
	int skip_byte;

	while (get_buffer(pb, preamble, VQA_PREAMBLE_SIZE) == VQA_PREAMBLE_SIZE) {
	chunk_type = AV_RB32(&preamble[0]);
	chunk_size = AV_RB32(&preamble[4]);
	skip_byte = chunk_size & 0x01;

	if ((chunk_type == SND1_TAG) \|\| (chunk_type == SND2_TAG) \|\| (chunk_type == VQFR_TAG)) {

	if (av_new_packet(pkt, chunk_size))
	return AVERROR(EIO);
	ret = get_buffer(pb, pkt->data, chunk_size);
	if (ret != chunk_size) {
	av_free_packet(pkt);
	return AVERROR(EIO);
	}

	if (chunk_type == SND2_TAG) {
	pkt->stream_index = wsvqa->audio_stream_index;
	/* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
	wsvqa->audio_frame_counter += (chunk_size * 2) / wsvqa->audio_channels;
	} else if(chunk_type == SND1_TAG) {
	pkt->stream_index = wsvqa->audio_stream_index;
	/* unpacked size is stored in header */
	wsvqa->audio_frame_counter += AV_RL16(pkt->data) / wsvqa->audio_channels;
	} else {
	pkt->stream_index = wsvqa->video_stream_index;
	wsvqa->video_pts += VQA_VIDEO_PTS_INC;
	}
	/* stay on 16-bit alignment */
	if (skip_byte)
	url_fseek(pb, 1, SEEK_CUR);

	return ret;
	} else {
	switch(chunk_type){
	case CMDS_TAG:
	case SND0_TAG:
	break;
	default:
	av_log(s, AV_LOG_INFO, "Skipping unknown chunk 0x%08X\n", chunk_type);
	}
	url_fseek(pb, chunk_size + skip_byte, SEEK_CUR);
	}
	}

	return ret;
	}

	#if CONFIG_WSAUD_DEMUXER
	AVInputFormat wsaud_demuxer = {
	"wsaud",
	NULL_IF_CONFIG_SMALL("Westwood Studios audio format"),
	sizeof(WsAudDemuxContext),
	wsaud_probe,
	wsaud_read_header,
	wsaud_read_packet,
	};
	#endif
	#if CONFIG_WSVQA_DEMUXER
	AVInputFormat wsvqa_demuxer = {
	"wsvqa",
	NULL_IF_CONFIG_SMALL("Westwood Studios VQA format"),
	sizeof(WsVqaDemuxContext),
	wsvqa_probe,
	wsvqa_read_header,
	wsvqa_read_packet,
	};
	#endif