| /* |
| * 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); |
| } |
| |
| 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 */ |
