[libav.git] / libavcodec / parser.c

/*
 * Audio and Video frame extraction
 * Copyright (c) 2003 Fabrice Bellard.
 * Copyright (c) 2003 Michael Niedermayer.
 *
 * 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
 */

#include "parser.h"

AVCodecParser *av_first_parser = NULL;

AVCodecParser* av_parser_next(AVCodecParser *p){
    if(p) return p->next;
    else  return av_first_parser;
}

void av_register_codec_parser(AVCodecParser *parser)
{
    parser->next = av_first_parser;
    av_first_parser = parser;
}

AVCodecParserContext *av_parser_init(int codec_id)
{
    AVCodecParserContext *s;
    AVCodecParser *parser;
    int ret;

    if(codec_id == CODEC_ID_NONE)
        return NULL;

    for(parser = av_first_parser; parser != NULL; parser = parser->next) {
        if (parser->codec_ids[0] == codec_id ||
            parser->codec_ids[1] == codec_id ||
            parser->codec_ids[2] == codec_id ||
            parser->codec_ids[3] == codec_id ||
            parser->codec_ids[4] == codec_id)
            goto found;
    }
    return NULL;
 found:
    s = av_mallocz(sizeof(AVCodecParserContext));
    if (!s)
        return NULL;
    s->parser = parser;
    s->priv_data = av_mallocz(parser->priv_data_size);
    if (!s->priv_data) {
        av_free(s);
        return NULL;
    }
    if (parser->parser_init) {
        ret = parser->parser_init(s);
        if (ret != 0) {
            av_free(s->priv_data);
            av_free(s);
            return NULL;
        }
    }
    s->fetch_timestamp=1;
    s->pict_type = FF_I_TYPE;
    return s;
}

/**
 *
 * @param buf           input
 * @param buf_size      input length, to signal EOF, this should be 0 (so that the last frame can be output)
 * @param pts           input presentation timestamp
 * @param dts           input decoding timestamp
 * @param poutbuf       will contain a pointer to the first byte of the output frame
 * @param poutbuf_size  will contain the length of the output frame
 * @return the number of bytes of the input bitstream used
 *
 * Example:
 * @code
 *   while(in_len){
 *       len = av_parser_parse(myparser, AVCodecContext, &data, &size,
 *                                       in_data, in_len,
 *                                       pts, dts);
 *       in_data += len;
 *       in_len  -= len;
 *
 *       if(size)
 *          decode_frame(data, size);
 *   }
 * @endcode
 */
int av_parser_parse(AVCodecParserContext *s,
                    AVCodecContext *avctx,
                    uint8_t **poutbuf, int *poutbuf_size,
                    const uint8_t *buf, int buf_size,
                    int64_t pts, int64_t dts)
{
    int index, i, k;
    uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];

    if (buf_size == 0) {
        /* padding is always necessary even if EOF, so we add it here */
        memset(dummy_buf, 0, sizeof(dummy_buf));
        buf = dummy_buf;
    } else {
        /* add a new packet descriptor */
        k = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
        s->cur_frame_start_index = k;
        s->cur_frame_offset[k] = s->cur_offset;
        s->cur_frame_end[k] = s->cur_offset + buf_size;
        s->cur_frame_pts[k] = pts;
        s->cur_frame_dts[k] = dts;
    }

    if (s->fetch_timestamp){
        s->fetch_timestamp=0;
        s->last_pts = s->pts;
        s->last_dts = s->dts;
        s->dts= s->pts= AV_NOPTS_VALUE;
        s->offset= 0;
        for(i = 0; i < AV_PARSER_PTS_NB; i++) {
            if (   s->next_frame_offset >= s->cur_frame_offset[i]
                &&(s->     frame_offset <  s->cur_frame_offset[i] || !s->frame_offset)
                && s->next_frame_offset <  s->cur_frame_end[i]){
                s->dts= s->cur_frame_dts[i];
                s->pts= s->cur_frame_pts[i];
                s->offset = s->next_frame_offset - s->cur_frame_offset[i];
            }
        }
    }

    /* WARNING: the returned index can be negative */
    index = s->parser->parser_parse(s, avctx, (const uint8_t **)poutbuf, poutbuf_size, buf, buf_size);
//av_log(NULL, AV_LOG_DEBUG, "parser: in:%"PRId64", %"PRId64", out:%"PRId64", %"PRId64", in:%d out:%d id:%d\n", pts, dts, s->last_pts, s->last_dts, buf_size, *poutbuf_size, avctx->codec_id);
    /* update the file pointer */
    if (*poutbuf_size) {
        /* fill the data for the current frame */
        s->frame_offset = s->next_frame_offset;

        /* offset of the next frame */
        s->next_frame_offset = s->cur_offset + index;
        s->fetch_timestamp=1;
    }
    if (index < 0)
        index = 0;
    s->cur_offset += index;
    return index;
}

/**
 *
 * @return 0 if the output buffer is a subset of the input, 1 if it is allocated and must be freed
 * @deprecated use AVBitstreamFilter
 */
int av_parser_change(AVCodecParserContext *s,
                     AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size, int keyframe){

    if(s && s->parser->split){
        if((avctx->flags & CODEC_FLAG_GLOBAL_HEADER) || (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)){
            int i= s->parser->split(avctx, buf, buf_size);
            buf += i;
            buf_size -= i;
        }
    }

    /* cast to avoid warning about discarding qualifiers */
    *poutbuf= (uint8_t *) buf;
    *poutbuf_size= buf_size;
    if(avctx->extradata){
        if(  (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER))
            /*||(s->pict_type != FF_I_TYPE && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_NOKEY))*/
            /*||(? && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_BEGIN)*/){
            int size= buf_size + avctx->extradata_size;
            *poutbuf_size= size;
            *poutbuf= av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);

            memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
            memcpy((*poutbuf) + avctx->extradata_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
            return 1;
        }
    }

    return 0;
}

void av_parser_close(AVCodecParserContext *s)
{
    if(s){
        if (s->parser->parser_close)
            s->parser->parser_close(s);
        av_free(s->priv_data);
        av_free(s);
    }
}

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

/**
 * combines the (truncated) bitstream to a complete frame
 * @returns -1 if no complete frame could be created, AVERROR(ENOMEM) if there was a memory allocation error
 */
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
{
#if 0
    if(pc->overread){
        printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
        printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);
    }
#endif

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

    /* flush remaining if EOF */
    if(!*buf_size && next == END_NOT_FOUND){
        next= 0;
    }

    pc->last_index= pc->index;

    /* copy into buffer end return */
    if(next == END_NOT_FOUND){
        void* new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, (*buf_size) + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);

        if(!new_buffer)
            return AVERROR(ENOMEM);
        pc->buffer = new_buffer;
        memcpy(&pc->buffer[pc->index], *buf, *buf_size);
        pc->index += *buf_size;
        return -1;
    }

    *buf_size=
    pc->overread_index= pc->index + next;

    /* append to buffer */
    if(pc->index){
        void* new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);

        if(!new_buffer)
            return AVERROR(ENOMEM);
        pc->buffer = new_buffer;
        memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
        pc->index = 0;
        *buf= pc->buffer;
    }

    /* store overread bytes */
    for(;next < 0; next++){
        pc->state = (pc->state<<8) | pc->buffer[pc->last_index + next];
        pc->overread++;
    }

#if 0
    if(pc->overread){
        printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
        printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);
    }
#endif

    return 0;
}

void ff_parse_close(AVCodecParserContext *s)
{
    ParseContext *pc = s->priv_data;

    av_free(pc->buffer);
}

void ff_parse1_close(AVCodecParserContext *s)
{
    ParseContext1 *pc1 = s->priv_data;

    av_free(pc1->pc.buffer);
    av_free(pc1->enc);
}

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

int ff_mpeg4video_split(AVCodecContext *avctx,
                           const uint8_t *buf, int buf_size)
{
    int i;
    uint32_t state= -1;

    for(i=0; i<buf_size; i++){
        state= (state<<8) | buf[i];
        if(state == 0x1B3 || state == 0x1B6)
            return i-3;
    }
    return 0;
}
Commit	Line	Data
8424cf50 FB	1	/*
	2	* Audio and Video frame extraction
	3	* Copyright (c) 2003 Fabrice Bellard.
	4	* Copyright (c) 2003 Michael Niedermayer.
	5	*
b78e7197 DB	6	* This file is part of FFmpeg.
	7	*
	8	* FFmpeg is free software; you can redistribute it and/or
8424cf50 FB	9	* modify it under the terms of the GNU Lesser General Public
8424cf50 FB	10	* License as published by the Free Software Foundation; either
b78e7197	11	* version 2.1 of the License, or (at your option) any later version.
8424cf50	12	*
b78e7197	13	* FFmpeg is distributed in the hope that it will be useful,
8424cf50 FB	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* Lesser General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU Lesser General Public
b78e7197	19	* License along with FFmpeg; if not, write to the Free Software
5509bffa	20	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
8424cf50	21	*/
1fddeecd	22
4067d81b	23	#include "parser.h"
8424cf50 FB	24
	25	AVCodecParser *av_first_parser = NULL;
	26
55b9e69a MN	27	AVCodecParser* av_parser_next(AVCodecParser *p){
	28	if(p) return p->next;
	29	else return av_first_parser;
	30	}
	31
8424cf50 FB	32	void av_register_codec_parser(AVCodecParser *parser)
	33	{
	34	parser->next = av_first_parser;
	35	av_first_parser = parser;
	36	}
	37
	38	AVCodecParserContext *av_parser_init(int codec_id)
	39	{
	40	AVCodecParserContext *s;
	41	AVCodecParser *parser;
	42	int ret;
115329f1	43
8845e427 MN	44	if(codec_id == CODEC_ID_NONE)
8845e427 MN	45	return NULL;
8424cf50 FB	46
	47	for(parser = av_first_parser; parser != NULL; parser = parser->next) {
	48	if (parser->codec_ids[0] == codec_id \|\|
	49	parser->codec_ids[1] == codec_id \|\|
99f06236 MN	50	parser->codec_ids[2] == codec_id \|\|
	51	parser->codec_ids[3] == codec_id \|\|
	52	parser->codec_ids[4] == codec_id)
8424cf50 FB	53	goto found;
	54	}
	55	return NULL;
	56	found:
	57	s = av_mallocz(sizeof(AVCodecParserContext));
	58	if (!s)
	59	return NULL;
	60	s->parser = parser;
	61	s->priv_data = av_mallocz(parser->priv_data_size);
	62	if (!s->priv_data) {
	63	av_free(s);
	64	return NULL;
	65	}
	66	if (parser->parser_init) {
	67	ret = parser->parser_init(s);
	68	if (ret != 0) {
	69	av_free(s->priv_data);
	70	av_free(s);
	71	return NULL;
	72	}
	73	}
a62aecce	74	s->fetch_timestamp=1;
adcb72b5	75	s->pict_type = FF_I_TYPE;
8424cf50 FB	76	return s;
	77	}
	78
6ab312da MN	79	/**
	80	*
	81	* @param buf input
	82	* @param buf_size input length, to signal EOF, this should be 0 (so that the last frame can be output)
	83	* @param pts input presentation timestamp
	84	* @param dts input decoding timestamp
	85	* @param poutbuf will contain a pointer to the first byte of the output frame
	86	* @param poutbuf_size will contain the length of the output frame
	87	* @return the number of bytes of the input bitstream used
	88	*
	89	* Example:
	90	* @code
	91	* while(in_len){
	92	* len = av_parser_parse(myparser, AVCodecContext, &data, &size,
	93	* in_data, in_len,
	94	* pts, dts);
	95	* in_data += len;
	96	* in_len -= len;
	97	*
832a7b63 MN	98	* if(size)
832a7b63 MN	99	* decode_frame(data, size);
6ab312da MN	100	* }
	101	* @endcode
	102	*/
115329f1	103	int av_parser_parse(AVCodecParserContext *s,
8424cf50	104	AVCodecContext *avctx,
115329f1	105	uint8_t *poutbuf, int poutbuf_size,
b84f2a35 FB	106	const uint8_t *buf, int buf_size,
b84f2a35 FB	107	int64_t pts, int64_t dts)
8424cf50	108	{
b84f2a35	109	int index, i, k;
6e45e928	110	uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];
115329f1	111
6e45e928 FB	112	if (buf_size == 0) {
	113	/* padding is always necessary even if EOF, so we add it here */
	114	memset(dummy_buf, 0, sizeof(dummy_buf));
	115	buf = dummy_buf;
b84f2a35 FB	116	} else {
	117	/* add a new packet descriptor */
	118	k = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
	119	s->cur_frame_start_index = k;
	120	s->cur_frame_offset[k] = s->cur_offset;
cb63a4b3	121	s->cur_frame_end[k] = s->cur_offset + buf_size;
b84f2a35 FB	122	s->cur_frame_pts[k] = pts;
b84f2a35 FB	123	s->cur_frame_dts[k] = dts;
cb63a4b3	124	}
b84f2a35	125
591569b5 MN	126	if (s->fetch_timestamp){
591569b5 MN	127	s->fetch_timestamp=0;
cb63a4b3 MN	128	s->last_pts = s->pts;
	129	s->last_dts = s->dts;
	130	s->dts= s->pts= AV_NOPTS_VALUE;
	131	s->offset= 0;
	132	for(i = 0; i < AV_PARSER_PTS_NB; i++) {
26f23725	133	if ( s->next_frame_offset >= s->cur_frame_offset[i]
cb63a4b3	134	&&(s-> frame_offset < s->cur_frame_offset[i] \|\| !s->frame_offset)
26f23725	135	&& s->next_frame_offset < s->cur_frame_end[i]){
cb63a4b3 MN	136	s->dts= s->cur_frame_dts[i];
cb63a4b3 MN	137	s->pts= s->cur_frame_pts[i];
26f23725	138	s->offset = s->next_frame_offset - s->cur_frame_offset[i];
cb63a4b3	139	}
b84f2a35	140	}
6e45e928 FB	141	}
6e45e928 FB	142
8424cf50	143	/* WARNING: the returned index can be negative */
c53d2d90	144	index = s->parser->parser_parse(s, avctx, (const uint8_t **)poutbuf, poutbuf_size, buf, buf_size);
949b1a13	145	//av_log(NULL, AV_LOG_DEBUG, "parser: in:%"PRId64", %"PRId64", out:%"PRId64", %"PRId64", in:%d out:%d id:%d\n", pts, dts, s->last_pts, s->last_dts, buf_size, *poutbuf_size, avctx->codec_id);
8424cf50 FB	146	/* update the file pointer */
8424cf50 FB	147	if (*poutbuf_size) {
b84f2a35	148	/* fill the data for the current frame */
26f23725	149	s->frame_offset = s->next_frame_offset;
115329f1	150
b84f2a35	151	/* offset of the next frame */
26f23725	152	s->next_frame_offset = s->cur_offset + index;
591569b5	153	s->fetch_timestamp=1;
8424cf50 FB	154	}
	155	if (index < 0)
	156	index = 0;
	157	s->cur_offset += index;
	158	return index;
	159	}
	160
73480a15 MN	161	/**
	162	*
	163	* @return 0 if the output buffer is a subset of the input, 1 if it is allocated and must be freed
748c2fca	164	* @deprecated use AVBitstreamFilter
73480a15	165	*/
90ad92b3 MN	166	int av_parser_change(AVCodecParserContext *s,
90ad92b3 MN	167	AVCodecContext *avctx,
115329f1	168	uint8_t *poutbuf, int poutbuf_size,
90ad92b3	169	const uint8_t *buf, int buf_size, int keyframe){
115329f1	170
90ad92b3	171	if(s && s->parser->split){
73480a15	172	if((avctx->flags & CODEC_FLAG_GLOBAL_HEADER) \|\| (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)){
90ad92b3 MN	173	int i= s->parser->split(avctx, buf, buf_size);
	174	buf += i;
	175	buf_size -= i;
	176	}
	177	}
	178
79396ac6 MR	179	/* cast to avoid warning about discarding qualifiers */
79396ac6 MR	180	poutbuf= (uint8_t ) buf;
90ad92b3 MN	181	*poutbuf_size= buf_size;
	182	if(avctx->extradata){
	183	if( (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER))
9701840b	184	/\|\|(s->pict_type != FF_I_TYPE && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_NOKEY))/
90ad92b3 MN	185	/\|\|(? && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_BEGIN)/){
	186	int size= buf_size + avctx->extradata_size;
	187	*poutbuf_size= size;
	188	*poutbuf= av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
115329f1	189
90ad92b3	190	memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
73480a15	191	memcpy((*poutbuf) + avctx->extradata_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
90ad92b3 MN	192	return 1;
	193	}
	194	}
	195
	196	return 0;
	197	}
	198
8424cf50 FB	199	void av_parser_close(AVCodecParserContext *s)
8424cf50 FB	200	{
99c1c388	201	if(s){
87b6ea84 MN	202	if (s->parser->parser_close)
	203	s->parser->parser_close(s);
	204	av_free(s->priv_data);
	205	av_free(s);
99c1c388	206	}
8424cf50 FB	207	}
	208
	209	/*****************************************************/
	210
8424cf50 FB	211	/**
8424cf50 FB	212	* combines the (truncated) bitstream to a complete frame
1f96bafb	213	* @returns -1 if no complete frame could be created, AVERROR(ENOMEM) if there was a memory allocation error
8424cf50	214	*/
c53d2d90	215	int ff_combine_frame(ParseContext pc, int next, const uint8_t buf, int buf_size)
8424cf50 FB	216	{
	217	#if 0
	218	if(pc->overread){
	219	printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
	220	printf("%X %X %X %X\n", (buf)[0], (buf)[1],(buf)[2],(buf)[3]);
	221	}
	222	#endif
	223
e42dba48	224	/* Copy overread bytes from last frame into buffer. */
8424cf50 FB	225	for(; pc->overread>0; pc->overread--){
	226	pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];
	227	}
f48c0551 MN	228
	229	/* flush remaining if EOF */
	230	if(!*buf_size && next == END_NOT_FOUND){
	231	next= 0;
	232	}
	233
8424cf50 FB	234	pc->last_index= pc->index;
	235
	236	/* copy into buffer end return */
	237	if(next == END_NOT_FOUND){
1f96bafb	238	void* new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, (*buf_size) + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
8424cf50	239
1f96bafb AG	240	if(!new_buffer)
	241	return AVERROR(ENOMEM);
	242	pc->buffer = new_buffer;
8424cf50 FB	243	memcpy(&pc->buffer[pc->index], buf, buf_size);
	244	pc->index += *buf_size;
	245	return -1;
	246	}
	247
	248	*buf_size=
	249	pc->overread_index= pc->index + next;
115329f1	250
8424cf50 FB	251	/* append to buffer */
8424cf50 FB	252	if(pc->index){
1f96bafb	253	void* new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
8424cf50	254
1f96bafb AG	255	if(!new_buffer)
	256	return AVERROR(ENOMEM);
	257	pc->buffer = new_buffer;
8424cf50 FB	258	memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
	259	pc->index = 0;
	260	*buf= pc->buffer;
	261	}
	262
	263	/* store overread bytes */
	264	for(;next < 0; next++){
	265	pc->state = (pc->state<<8) \| pc->buffer[pc->last_index + next];
	266	pc->overread++;
	267	}
	268
	269	#if 0
	270	if(pc->overread){
	271	printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
	272	printf("%X %X %X %X\n", (buf)[0], (buf)[1],(buf)[2],(buf)[3]);
	273	}
	274	#endif
	275
	276	return 0;
	277	}
	278
e4cb187d	279	void ff_parse_close(AVCodecParserContext *s)
8424cf50	280	{
e4cb187d	281	ParseContext *pc = s->priv_data;
8424cf50 FB	282
8424cf50 FB	283	av_free(pc->buffer);
8424cf50 FB	284	}
8424cf50 FB	285
4067d81b	286	void ff_parse1_close(AVCodecParserContext *s)
8424cf50	287	{
e4cb187d	288	ParseContext1 *pc1 = s->priv_data;
8424cf50	289
e4cb187d MN	290	av_free(pc1->pc.buffer);
e4cb187d MN	291	av_free(pc1->enc);
8424cf50 FB	292	}
8424cf50 FB	293
e4cb187d MN	294	/*************************/
e4cb187d MN	295
d136d2fc	296	int ff_mpeg4video_split(AVCodecContext *avctx,
90ad92b3 MN	297	const uint8_t *buf, int buf_size)
	298	{
	299	int i;
	300	uint32_t state= -1;
115329f1	301
90ad92b3 MN	302	for(i=0; i<buf_size; i++){
	303	state= (state<<8) \| buf[i];
	304	if(state == 0x1B3 \|\| state == 0x1B6)
73480a15	305	return i-3;
90ad92b3 MN	306	}
	307	return 0;
	308	}