RepoMirrors
/
ffmpeg
mirror of https://git.ffmpeg.org/ffmpeg.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
ffmpeg/libavcodec/dca_parser.c

252 lines
8.1 KiB
C
Raw Blame History

/*
* DCA parser
* Copyright (C) 2004 Gildas Bazin
* Copyright (C) 2004 Benjamin Zores
* Copyright (C) 2006 Benjamin Larsson
* Copyright (C) 2007 Konstantin Shishkov
*
* 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 "dca.h"
#include "dca_syncwords.h"
#include "get_bits.h"
#include "parser.h"
typedef struct DCAParseContext {
ParseContext pc;
uint32_t lastmarker;
int size;
int framesize;
} DCAParseContext;
#define IS_CORE_MARKER(state) \
(((state & 0xFFFFFFFFF0FF) == (((uint64_t)DCA_SYNCWORD_CORE_14B_LE << 16) | 0xF007)) || \
((state & 0xFFFFFFFFFFF0) == (((uint64_t)DCA_SYNCWORD_CORE_14B_BE << 16) | 0x07F0)) || \
((state & 0xFFFFFFFF00FC) == (((uint64_t)DCA_SYNCWORD_CORE_LE << 16) | 0x00FC)) || \
((state & 0xFFFFFFFFFC00) == (((uint64_t)DCA_SYNCWORD_CORE_BE << 16) | 0xFC00)))
#define IS_EXSS_MARKER(state) ((state & 0xFFFFFFFF) == DCA_SYNCWORD_SUBSTREAM)
#define IS_MARKER(state) (IS_CORE_MARKER(state) || IS_EXSS_MARKER(state))
#define CORE_MARKER(state) ((state >> 16) & 0xFFFFFFFF)
#define EXSS_MARKER(state) (state & 0xFFFFFFFF)
#define STATE_LE(state) (((state & 0xFF00FF00) >> 8) | ((state & 0x00FF00FF) << 8))
#define STATE_14(state) (((state & 0x3FFF0000) >> 8) | ((state & 0x00003FFF) >> 6))
#define CORE_FRAMESIZE(state) (((state >> 4) & 0x3FFF) + 1)
#define EXSS_FRAMESIZE(state) ((state & 0x2000000000) ? \
((state >> 5) & 0xFFFFF) + 1 : \
((state >> 13) & 0x0FFFF) + 1)
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
static int dca_find_frame_end(DCAParseContext *pc1, const uint8_t *buf,
int buf_size)
{
int start_found, size, i;
uint64_t state;
ParseContext *pc = &pc1->pc;
start_found = pc->frame_start_found;
state = pc->state64;
size = pc1->size;
i = 0;
if (!start_found) {
for (i = 0; i < buf_size; i++) {
state = (state << 8) | buf[i];
if (IS_MARKER(state)) {
if (!pc1->lastmarker ||
pc1->lastmarker == CORE_MARKER(state) ||
pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM) {
start_found = 1;
if (IS_EXSS_MARKER(state))
pc1->lastmarker = EXSS_MARKER(state);
else
pc1->lastmarker = CORE_MARKER(state);
i++;
break;
}
}
}
}
if (start_found) {
for (; i < buf_size; i++) {
size++;
state = (state << 8) | buf[i];
if (start_found == 1) {
switch (pc1->lastmarker) {
case DCA_SYNCWORD_CORE_BE:
if (size == 2) {
pc1->framesize = CORE_FRAMESIZE(state);
start_found = 2;
}
break;
case DCA_SYNCWORD_CORE_LE:
if (size == 2) {
pc1->framesize = CORE_FRAMESIZE(STATE_LE(state));
start_found = 2;
}
break;
case DCA_SYNCWORD_CORE_14B_BE:
if (size == 4) {
pc1->framesize = CORE_FRAMESIZE(STATE_14(state)) * 8 / 14 * 2;
start_found = 2;
}
break;
case DCA_SYNCWORD_CORE_14B_LE:
if (size == 4) {
pc1->framesize = CORE_FRAMESIZE(STATE_14(STATE_LE(state))) * 8 / 14 * 2;
start_found = 2;
}
break;
case DCA_SYNCWORD_SUBSTREAM:
if (size == 6) {
pc1->framesize = EXSS_FRAMESIZE(state);
start_found = 2;
}
break;
default:
av_assert0(0);
}
continue;
}
if (pc1->lastmarker == DCA_SYNCWORD_CORE_BE) {
if (pc1->framesize > size + 2)
continue;
if (start_found == 2 && IS_EXSS_MARKER(state)) {
pc1->framesize = size + 2;
start_found = 3;
continue;
}
if (start_found == 3) {
if (size == pc1->framesize + 4) {
pc1->framesize += EXSS_FRAMESIZE(state);
start_found = 4;
}
continue;
}
}
if (pc1->framesize > size)
continue;
if (IS_MARKER(state) &&
(pc1->lastmarker == CORE_MARKER(state) ||
pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM)) {
pc->frame_start_found = 0;
pc->state64 = -1;
pc1->size = 0;
return IS_EXSS_MARKER(state) ? i - 3 : i - 5;
}
}
}
pc->frame_start_found = start_found;
pc->state64 = state;
pc1->size = size;
return END_NOT_FOUND;
}
static av_cold int dca_parse_init(AVCodecParserContext *s)
{
DCAParseContext *pc1 = s->priv_data;
pc1->lastmarker = 0;
return 0;
}
static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
int *sample_rate)
{
GetBitContext gb;
uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
int ret, sample_blocks;
if (buf_size < 12)
return AVERROR_INVALIDDATA;
if ((ret = avpriv_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
return ret;
init_get_bits(&gb, hdr, 96);
skip_bits_long(&gb, 39);
sample_blocks = get_bits(&gb, 7) + 1;
if (sample_blocks < 8)
return AVERROR_INVALIDDATA;
*duration = 256 * (sample_blocks / 8);
skip_bits(&gb, 20);
*sample_rate = avpriv_dca_sample_rates[get_bits(&gb, 4)];
if (*sample_rate == 0)
return AVERROR_INVALIDDATA;
return 0;
}
static int dca_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
DCAParseContext *pc1 = s->priv_data;
ParseContext *pc = &pc1->pc;
int next, duration, sample_rate;
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next = buf_size;
} else {
next = dca_find_frame_end(pc1, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
}
/* read the duration and sample rate from the frame header */
if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {
if (!avctx->sample_rate)
avctx->sample_rate = sample_rate;
s->duration = av_rescale(duration, avctx->sample_rate, sample_rate);
} else
s->duration = 0;
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
AVCodecParser ff_dca_parser = {
.codec_ids = { AV_CODEC_ID_DTS },
.priv_data_size = sizeof(DCAParseContext),
.parser_init = dca_parse_init,
.parser_parse = dca_parse,
.parser_close = ff_parse_close,
};
Reference in New Issue View Git Blame Copy Permalink