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342 lines
10 KiB
C
Executable File
342 lines
10 KiB
C
Executable File
/*
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* Copyright (c) 2012 Justin Ruggles
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Vorbis audio parser
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*
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* Determines the duration for each packet.
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*/
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#include "libavutil/log.h"
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#include "get_bits.h"
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#include "parser.h"
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#include "xiph.h"
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#include "vorbis_parser_internal.h"
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static const AVClass vorbis_parser_class = {
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.class_name = "Vorbis parser",
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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};
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static int parse_id_header(AVVorbisParseContext *s,
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const uint8_t *buf, int buf_size)
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{
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/* Id header should be 30 bytes */
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if (buf_size < 30) {
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av_log(s, AV_LOG_ERROR, "Id header is too short\n");
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return AVERROR_INVALIDDATA;
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}
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/* make sure this is the Id header */
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if (buf[0] != 1) {
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av_log(s, AV_LOG_ERROR, "Wrong packet type in Id header\n");
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return AVERROR_INVALIDDATA;
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}
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/* check for header signature */
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if (memcmp(&buf[1], "vorbis", 6)) {
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av_log(s, AV_LOG_ERROR, "Invalid packet signature in Id header\n");
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return AVERROR_INVALIDDATA;
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}
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if (!(buf[29] & 0x1)) {
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av_log(s, AV_LOG_ERROR, "Invalid framing bit in Id header\n");
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return AVERROR_INVALIDDATA;
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}
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s->blocksize[0] = 1 << (buf[28] & 0xF);
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s->blocksize[1] = 1 << (buf[28] >> 4);
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return 0;
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}
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static int parse_setup_header(AVVorbisParseContext *s,
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const uint8_t *buf, int buf_size)
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{
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GetBitContext gb, gb0;
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uint8_t *rev_buf;
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int i, ret = 0;
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int got_framing_bit, mode_count, got_mode_header, last_mode_count = 0;
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/* avoid overread */
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if (buf_size < 7) {
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av_log(s, AV_LOG_ERROR, "Setup header is too short\n");
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return AVERROR_INVALIDDATA;
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}
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/* make sure this is the Setup header */
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if (buf[0] != 5) {
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av_log(s, AV_LOG_ERROR, "Wrong packet type in Setup header\n");
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return AVERROR_INVALIDDATA;
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}
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/* check for header signature */
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if (memcmp(&buf[1], "vorbis", 6)) {
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av_log(s, AV_LOG_ERROR, "Invalid packet signature in Setup header\n");
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return AVERROR_INVALIDDATA;
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}
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/* reverse bytes so we can easily read backwards with get_bits() */
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if (!(rev_buf = av_malloc(buf_size))) {
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av_log(s, AV_LOG_ERROR, "Out of memory\n");
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return AVERROR(ENOMEM);
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}
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for (i = 0; i < buf_size; i++)
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rev_buf[i] = buf[buf_size - 1 - i];
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init_get_bits(&gb, rev_buf, buf_size * 8);
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got_framing_bit = 0;
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while (get_bits_left(&gb) > 97) {
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if (get_bits1(&gb)) {
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got_framing_bit = get_bits_count(&gb);
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break;
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}
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}
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if (!got_framing_bit) {
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av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
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ret = AVERROR_INVALIDDATA;
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goto bad_header;
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}
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/* Now we search backwards to find possible valid mode counts. This is not
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* fool-proof because we could have false positive matches and read too
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* far, but there isn't really any way to be sure without parsing through
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* all the many variable-sized fields before the modes. This approach seems
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* to work well in testing, and it is similar to how it is handled in
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* liboggz. */
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mode_count = 0;
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got_mode_header = 0;
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while (get_bits_left(&gb) >= 97) {
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if (get_bits(&gb, 8) > 63 || get_bits(&gb, 16) || get_bits(&gb, 16))
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break;
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skip_bits(&gb, 1);
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mode_count++;
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if (mode_count > 64)
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break;
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gb0 = gb;
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if (get_bits(&gb0, 6) + 1 == mode_count) {
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got_mode_header = 1;
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last_mode_count = mode_count;
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}
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}
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if (!got_mode_header) {
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av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
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ret = AVERROR_INVALIDDATA;
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goto bad_header;
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}
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/* All samples I've seen use <= 2 modes, so ask for a sample if we find
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* more than that, as it is most likely a false positive. If we get any
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* we may need to approach this the long way and parse the whole Setup
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* header, but I hope very much that it never comes to that. */
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if (last_mode_count > 2) {
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avpriv_request_sample(s,
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"%d modes (either a false positive or a "
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"sample from an unknown encoder)",
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last_mode_count);
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}
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/* We're limiting the mode count to 63 so that we know that the previous
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* block flag will be in the first packet byte. */
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if (last_mode_count > 63) {
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av_log(s, AV_LOG_ERROR, "Unsupported mode count: %d\n",
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last_mode_count);
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ret = AVERROR_INVALIDDATA;
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goto bad_header;
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}
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s->mode_count = mode_count = last_mode_count;
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/* Determine the number of bits required to code the mode and turn that
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* into a bitmask to directly access the mode from the first frame byte. */
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s->mode_mask = ((1 << (av_log2(mode_count - 1) + 1)) - 1) << 1;
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/* The previous window flag is the next bit after the mode */
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s->prev_mask = (s->mode_mask | 0x1) + 1;
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init_get_bits(&gb, rev_buf, buf_size * 8);
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skip_bits_long(&gb, got_framing_bit);
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for (i = mode_count - 1; i >= 0; i--) {
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skip_bits_long(&gb, 40);
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s->mode_blocksize[i] = get_bits1(&gb);
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}
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bad_header:
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av_free(rev_buf);
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return ret;
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}
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static int vorbis_parse_init(AVVorbisParseContext *s,
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const uint8_t *extradata, int extradata_size)
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{
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const uint8_t *header_start[3];
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int header_len[3];
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int ret;
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s->class = &vorbis_parser_class;
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s->extradata_parsed = 1;
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if ((ret = avpriv_split_xiph_headers(extradata,
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extradata_size, 30,
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header_start, header_len)) < 0) {
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av_log(s, AV_LOG_ERROR, "Extradata corrupt.\n");
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return ret;
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}
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if ((ret = parse_id_header(s, header_start[0], header_len[0])) < 0)
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return ret;
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if ((ret = parse_setup_header(s, header_start[2], header_len[2])) < 0)
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return ret;
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s->valid_extradata = 1;
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s->previous_blocksize = s->blocksize[s->mode_blocksize[0]];
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return 0;
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}
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int av_vorbis_parse_frame_flags(AVVorbisParseContext *s, const uint8_t *buf,
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int buf_size, int *flags)
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{
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int duration = 0;
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if (s->valid_extradata && buf_size > 0) {
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int mode, current_blocksize;
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int previous_blocksize = s->previous_blocksize;
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if (buf[0] & 1) {
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/* If the user doesn't care about special packets, it's a bad one. */
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if (!flags)
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goto bad_packet;
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/* Set the flag for which kind of special packet it is. */
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if (buf[0] == 1)
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*flags |= VORBIS_FLAG_HEADER;
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else if (buf[0] == 3)
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*flags |= VORBIS_FLAG_COMMENT;
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else if (buf[0] == 5)
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*flags |= VORBIS_FLAG_SETUP;
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else
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goto bad_packet;
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/* Special packets have no duration. */
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return 0;
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bad_packet:
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av_log(s, AV_LOG_ERROR, "Invalid packet\n");
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return AVERROR_INVALIDDATA;
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}
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if (s->mode_count == 1)
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mode = 0;
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else
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mode = (buf[0] & s->mode_mask) >> 1;
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if (mode >= s->mode_count) {
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av_log(s, AV_LOG_ERROR, "Invalid mode in packet\n");
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return AVERROR_INVALIDDATA;
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}
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if(s->mode_blocksize[mode]){
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int flag = !!(buf[0] & s->prev_mask);
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previous_blocksize = s->blocksize[flag];
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}
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current_blocksize = s->blocksize[s->mode_blocksize[mode]];
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duration = (previous_blocksize + current_blocksize) >> 2;
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s->previous_blocksize = current_blocksize;
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}
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return duration;
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}
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int av_vorbis_parse_frame(AVVorbisParseContext *s, const uint8_t *buf,
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int buf_size)
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{
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return av_vorbis_parse_frame_flags(s, buf, buf_size, NULL);
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}
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void av_vorbis_parse_reset(AVVorbisParseContext *s)
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{
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if (s->valid_extradata)
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s->previous_blocksize = s->blocksize[0];
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}
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void av_vorbis_parse_free(AVVorbisParseContext **s)
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{
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av_freep(s);
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}
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AVVorbisParseContext *av_vorbis_parse_init(const uint8_t *extradata,
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int extradata_size)
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{
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AVVorbisParseContext *s = av_mallocz(sizeof(*s));
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int ret;
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if (!s)
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return NULL;
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ret = vorbis_parse_init(s, extradata, extradata_size);
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if (ret < 0) {
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av_vorbis_parse_free(&s);
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return NULL;
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}
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return s;
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}
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#if CONFIG_VORBIS_PARSER
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typedef struct VorbisParseContext {
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AVVorbisParseContext *vp;
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} VorbisParseContext;
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static int vorbis_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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VorbisParseContext *s = s1->priv_data;
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int duration;
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if (!s->vp && avctx->extradata && avctx->extradata_size) {
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s->vp = av_vorbis_parse_init(avctx->extradata, avctx->extradata_size);
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}
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if (!s->vp)
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goto end;
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if ((duration = av_vorbis_parse_frame(s->vp, buf, buf_size)) >= 0)
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s1->duration = duration;
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end:
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/* always return the full packet. this parser isn't doing any splitting or
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combining, only packet analysis */
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return buf_size;
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}
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static void vorbis_parser_close(AVCodecParserContext *ctx)
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{
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VorbisParseContext *s = ctx->priv_data;
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av_vorbis_parse_free(&s->vp);
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}
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AVCodecParser ff_vorbis_parser = {
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.codec_ids = { AV_CODEC_ID_VORBIS },
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.priv_data_size = sizeof(VorbisParseContext),
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.parser_parse = vorbis_parse,
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.parser_close = vorbis_parser_close,
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};
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#endif /* CONFIG_VORBIS_PARSER */
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