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ffmpeg/libavcodec/vorbis_parser.c

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/*
* Copyright (c) 2012 Justin Ruggles
*
* 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
* Vorbis audio parser
*
* Determines the duration for each packet.
*/
#include "libavutil/log.h"
#include "get_bits.h"
#include "parser.h"
#include "xiph.h"
#include "vorbis_parser_internal.h"
static const AVClass vorbis_parser_class = {
.class_name = "Vorbis parser",
.item_name = av_default_item_name,
.version = LIBAVUTIL_VERSION_INT,
};
static int parse_id_header(AVVorbisParseContext *s,
const uint8_t *buf, int buf_size)
{
/* Id header should be 30 bytes */
if (buf_size < 30) {
av_log(s, AV_LOG_ERROR, "Id header is too short\n");
return AVERROR_INVALIDDATA;
}
/* make sure this is the Id header */
if (buf[0] != 1) {
av_log(s, AV_LOG_ERROR, "Wrong packet type in Id header\n");
return AVERROR_INVALIDDATA;
}
/* check for header signature */
if (memcmp(&buf[1], "vorbis", 6)) {
av_log(s, AV_LOG_ERROR, "Invalid packet signature in Id header\n");
return AVERROR_INVALIDDATA;
}
if (!(buf[29] & 0x1)) {
av_log(s, AV_LOG_ERROR, "Invalid framing bit in Id header\n");
return AVERROR_INVALIDDATA;
}
s->blocksize[0] = 1 << (buf[28] & 0xF);
s->blocksize[1] = 1 << (buf[28] >> 4);
return 0;
}
static int parse_setup_header(AVVorbisParseContext *s,
const uint8_t *buf, int buf_size)
{
GetBitContext gb, gb0;
uint8_t *rev_buf;
int i, ret = 0;
int got_framing_bit, mode_count, got_mode_header, last_mode_count = 0;
/* avoid overread */
if (buf_size < 7) {
av_log(s, AV_LOG_ERROR, "Setup header is too short\n");
return AVERROR_INVALIDDATA;
}
/* make sure this is the Setup header */
if (buf[0] != 5) {
av_log(s, AV_LOG_ERROR, "Wrong packet type in Setup header\n");
return AVERROR_INVALIDDATA;
}
/* check for header signature */
if (memcmp(&buf[1], "vorbis", 6)) {
av_log(s, AV_LOG_ERROR, "Invalid packet signature in Setup header\n");
return AVERROR_INVALIDDATA;
}
/* reverse bytes so we can easily read backwards with get_bits() */
if (!(rev_buf = av_malloc(buf_size))) {
av_log(s, AV_LOG_ERROR, "Out of memory\n");
return AVERROR(ENOMEM);
}
for (i = 0; i < buf_size; i++)
rev_buf[i] = buf[buf_size - 1 - i];
init_get_bits(&gb, rev_buf, buf_size * 8);
got_framing_bit = 0;
while (get_bits_left(&gb) > 97) {
if (get_bits1(&gb)) {
got_framing_bit = get_bits_count(&gb);
break;
}
}
if (!got_framing_bit) {
av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
ret = AVERROR_INVALIDDATA;
goto bad_header;
}
/* Now we search backwards to find possible valid mode counts. This is not
* fool-proof because we could have false positive matches and read too
* far, but there isn't really any way to be sure without parsing through
* all the many variable-sized fields before the modes. This approach seems
* to work well in testing, and it is similar to how it is handled in
* liboggz. */
mode_count = 0;
got_mode_header = 0;
while (get_bits_left(&gb) >= 97) {
if (get_bits(&gb, 8) > 63 || get_bits(&gb, 16) || get_bits(&gb, 16))
break;
skip_bits(&gb, 1);
mode_count++;
if (mode_count > 64)
break;
gb0 = gb;
if (get_bits(&gb0, 6) + 1 == mode_count) {
got_mode_header = 1;
last_mode_count = mode_count;
}
}
if (!got_mode_header) {
av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
ret = AVERROR_INVALIDDATA;
goto bad_header;
}
/* All samples I've seen use <= 2 modes, so ask for a sample if we find
* more than that, as it is most likely a false positive. If we get any
* we may need to approach this the long way and parse the whole Setup
* header, but I hope very much that it never comes to that. */
if (last_mode_count > 2) {
avpriv_request_sample(s,
"%d modes (either a false positive or a "
"sample from an unknown encoder)",
last_mode_count);
}
/* We're limiting the mode count to 63 so that we know that the previous
* block flag will be in the first packet byte. */
if (last_mode_count > 63) {
av_log(s, AV_LOG_ERROR, "Unsupported mode count: %d\n",
last_mode_count);
ret = AVERROR_INVALIDDATA;
goto bad_header;
}
s->mode_count = mode_count = last_mode_count;
/* Determine the number of bits required to code the mode and turn that
* into a bitmask to directly access the mode from the first frame byte. */
s->mode_mask = ((1 << (av_log2(mode_count - 1) + 1)) - 1) << 1;
/* The previous window flag is the next bit after the mode */
s->prev_mask = (s->mode_mask | 0x1) + 1;
init_get_bits(&gb, rev_buf, buf_size * 8);
skip_bits_long(&gb, got_framing_bit);
for (i = mode_count - 1; i >= 0; i--) {
skip_bits_long(&gb, 40);
s->mode_blocksize[i] = get_bits1(&gb);
}
bad_header:
av_free(rev_buf);
return ret;
}
static int vorbis_parse_init(AVVorbisParseContext *s,
const uint8_t *extradata, int extradata_size)
{
const uint8_t *header_start[3];
int header_len[3];
int ret;
s->class = &vorbis_parser_class;
s->extradata_parsed = 1;
if ((ret = avpriv_split_xiph_headers(extradata,
extradata_size, 30,
header_start, header_len)) < 0) {
av_log(s, AV_LOG_ERROR, "Extradata corrupt.\n");
return ret;
}
if ((ret = parse_id_header(s, header_start[0], header_len[0])) < 0)
return ret;
if ((ret = parse_setup_header(s, header_start[2], header_len[2])) < 0)
return ret;
s->valid_extradata = 1;
s->previous_blocksize = s->blocksize[s->mode_blocksize[0]];
return 0;
}
int av_vorbis_parse_frame_flags(AVVorbisParseContext *s, const uint8_t *buf,
int buf_size, int *flags)
{
int duration = 0;
if (s->valid_extradata && buf_size > 0) {
int mode, current_blocksize;
int previous_blocksize = s->previous_blocksize;
if (buf[0] & 1) {
/* If the user doesn't care about special packets, it's a bad one. */
if (!flags)
goto bad_packet;
/* Set the flag for which kind of special packet it is. */
if (buf[0] == 1)
*flags |= VORBIS_FLAG_HEADER;
else if (buf[0] == 3)
*flags |= VORBIS_FLAG_COMMENT;
else if (buf[0] == 5)
*flags |= VORBIS_FLAG_SETUP;
else
goto bad_packet;
/* Special packets have no duration. */
return 0;
bad_packet:
av_log(s, AV_LOG_ERROR, "Invalid packet\n");
return AVERROR_INVALIDDATA;
}
if (s->mode_count == 1)
mode = 0;
else
mode = (buf[0] & s->mode_mask) >> 1;
if (mode >= s->mode_count) {
av_log(s, AV_LOG_ERROR, "Invalid mode in packet\n");
return AVERROR_INVALIDDATA;
}
if(s->mode_blocksize[mode]){
int flag = !!(buf[0] & s->prev_mask);
previous_blocksize = s->blocksize[flag];
}
current_blocksize = s->blocksize[s->mode_blocksize[mode]];
duration = (previous_blocksize + current_blocksize) >> 2;
s->previous_blocksize = current_blocksize;
}
return duration;
}
int av_vorbis_parse_frame(AVVorbisParseContext *s, const uint8_t *buf,
int buf_size)
{
return av_vorbis_parse_frame_flags(s, buf, buf_size, NULL);
}
void av_vorbis_parse_reset(AVVorbisParseContext *s)
{
if (s->valid_extradata)
s->previous_blocksize = s->blocksize[0];
}
void av_vorbis_parse_free(AVVorbisParseContext **s)
{
av_freep(s);
}
AVVorbisParseContext *av_vorbis_parse_init(const uint8_t *extradata,
int extradata_size)
{
AVVorbisParseContext *s = av_mallocz(sizeof(*s));
int ret;
if (!s)
return NULL;
ret = vorbis_parse_init(s, extradata, extradata_size);
if (ret < 0) {
av_vorbis_parse_free(&s);
return NULL;
}
return s;
}
#if CONFIG_VORBIS_PARSER
typedef struct VorbisParseContext {
AVVorbisParseContext *vp;
} VorbisParseContext;
static int vorbis_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
VorbisParseContext *s = s1->priv_data;
int duration;
if (!s->vp && avctx->extradata && avctx->extradata_size) {
s->vp = av_vorbis_parse_init(avctx->extradata, avctx->extradata_size);
}
if (!s->vp)
goto end;
if ((duration = av_vorbis_parse_frame(s->vp, buf, buf_size)) >= 0)
s1->duration = duration;
end:
/* always return the full packet. this parser isn't doing any splitting or
combining, only packet analysis */
*poutbuf = buf;
*poutbuf_size = buf_size;
return buf_size;
}
static void vorbis_parser_close(AVCodecParserContext *ctx)
{
VorbisParseContext *s = ctx->priv_data;
av_vorbis_parse_free(&s->vp);
}
const AVCodecParser ff_vorbis_parser = {
.codec_ids = { AV_CODEC_ID_VORBIS },
.priv_data_size = sizeof(VorbisParseContext),
.parser_parse = vorbis_parse,
.parser_close = vorbis_parser_close,
};
#endif /* CONFIG_VORBIS_PARSER */
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