From 5602a464c9f9e3c0922f5cfeccaf2fa1c40b2401 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Sun, 15 Jan 2012 13:38:03 -0500 Subject: avcodec: add a Vorbis parser to get packet duration This also allows for removing some of the Vorbis-related hacks. --- libavcodec/vorbis_parser.c | 270 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 270 insertions(+) create mode 100644 libavcodec/vorbis_parser.c (limited to 'libavcodec/vorbis_parser.c') diff --git a/libavcodec/vorbis_parser.c b/libavcodec/vorbis_parser.c new file mode 100644 index 0000000000..f8d92e04d0 --- /dev/null +++ b/libavcodec/vorbis_parser.c @@ -0,0 +1,270 @@ +/* + * Copyright (c) 2012 Justin Ruggles + * + * This file is part of Libav. + * + * Libav 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. + * + * Libav 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 Libav; 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 "get_bits.h" +#include "parser.h" +#include "xiph.h" +#include "vorbis_parser.h" + +static int parse_id_header(AVCodecContext *avctx, VorbisParseContext *s, + const uint8_t *buf, int buf_size) +{ + /* Id header should be 30 bytes */ + if (buf_size < 30) { + av_log(avctx, 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(avctx, 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(avctx, AV_LOG_ERROR, "Invalid packet signature in Id header\n"); + return AVERROR_INVALIDDATA; + } + + if (!(buf[29] & 0x1)) { + av_log(avctx, 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(AVCodecContext *avctx, VorbisParseContext *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(avctx, 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(avctx, 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(avctx, 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(avctx, 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(avctx, 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(avctx, 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) { + av_log_ask_for_sample(avctx, "%d modes found. This is either a false " + "positive or a sample from an unknown encoder.\n", + 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(avctx, 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] = s->blocksize[get_bits1(&gb)]; + } + +bad_header: + av_free(rev_buf); + return ret; +} + +int avpriv_vorbis_parse_extradata(AVCodecContext *avctx, VorbisParseContext *s) +{ + uint8_t *header_start[3]; + int header_len[3]; + int ret; + + s->avctx = avctx; + s->extradata_parsed = 1; + + if ((ret = avpriv_split_xiph_headers(avctx->extradata, + avctx->extradata_size, 30, + header_start, header_len)) < 0) { + av_log(avctx, AV_LOG_ERROR, "Extradata corrupt.\n"); + return ret; + } + + if ((ret = parse_id_header(avctx, s, header_start[0], header_len[0])) < 0) + return ret; + + if ((ret = parse_setup_header(avctx, s, header_start[2], header_len[2])) < 0) + return ret; + + s->valid_extradata = 1; + s->previous_blocksize = s->mode_blocksize[0]; + + return 0; +} + +int avpriv_vorbis_parse_frame(VorbisParseContext *s, const uint8_t *buf, + int buf_size) +{ + int duration = 0; + + if (s->valid_extradata && buf_size > 0) { + int mode, current_blocksize; + int previous_blocksize = s->previous_blocksize; + + if (buf[0] & 1) { + av_log(s->avctx, 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->avctx, AV_LOG_ERROR, "Invalid mode in packet\n"); + return AVERROR_INVALIDDATA; + } + if (mode) { + int flag = !!(buf[0] & s->prev_mask); + previous_blocksize = s->blocksize[flag]; + } + current_blocksize = s->mode_blocksize[mode]; + duration = (previous_blocksize + current_blocksize) >> 2; + s->previous_blocksize = current_blocksize; + } + + return duration; +} + +void avpriv_vorbis_parse_reset(VorbisParseContext *s) +{ + if (s->valid_extradata) + s->previous_blocksize = s->mode_blocksize[0]; +} + +#if CONFIG_VORBIS_PARSER +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->extradata_parsed && avctx->extradata && avctx->extradata_size) + if (avpriv_vorbis_parse_extradata(avctx, s)) + goto end; + + if ((duration = avpriv_vorbis_parse_frame(s, 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; +} + +AVCodecParser ff_vorbis_parser = { + .codec_ids = { CODEC_ID_VORBIS }, + .priv_data_size = sizeof(VorbisParseContext), + .parser_parse = vorbis_parse, +}; +#endif /* CONFIG_VORBIS_PARSER */ -- cgit v1.2.3