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191dd219d9
Check extended sync word for 16-bit LE and BE core streams to reduce probability of alias sync detection. Previously sync word extension was checked only for 14-bit streams. This follows up the similar change in avcodec/dca_parser. Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
/*
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* RAW DTS demuxer
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* Copyright (c) 2008 Benjamin Larsson
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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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#include "libavcodec/bytestream.h"
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#include "libavcodec/dca.h"
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#include "libavcodec/dca_syncwords.h"
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#include "libavcodec/get_bits.h"
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#include "avformat.h"
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#include "rawdec.h"
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static int dts_probe(AVProbeData *p)
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{
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const uint8_t *buf, *bufp;
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uint32_t state = -1;
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int markers[4*16] = {0};
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int sum, max, i;
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int64_t diff = 0;
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uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
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buf = p->buf + FFMIN(4096, p->buf_size);
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for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
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int marker, sample_blocks, sample_rate, sr_code, framesize;
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int lfe;
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GetBitContext gb;
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bufp = buf;
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state = (state << 16) | bytestream_get_be16(&bufp);
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if (buf - p->buf >= 4)
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diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
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/* regular bitstream */
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if (state == DCA_SYNCWORD_CORE_BE &&
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(bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
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marker = 0;
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else if (state == DCA_SYNCWORD_CORE_LE &&
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(bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
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marker = 1;
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/* 14 bits big-endian bitstream */
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else if (state == DCA_SYNCWORD_CORE_14B_BE &&
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(bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
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marker = 2;
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/* 14 bits little-endian bitstream */
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else if (state == DCA_SYNCWORD_CORE_14B_LE &&
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(bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
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marker = 3;
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else
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continue;
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if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0)
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continue;
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init_get_bits(&gb, hdr, 96);
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skip_bits_long(&gb, 39);
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sample_blocks = get_bits(&gb, 7) + 1;
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if (sample_blocks < 8)
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continue;
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framesize = get_bits(&gb, 14) + 1;
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if (framesize < 95)
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continue;
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skip_bits(&gb, 6);
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sr_code = get_bits(&gb, 4);
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sample_rate = avpriv_dca_sample_rates[sr_code];
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if (sample_rate == 0)
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continue;
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get_bits(&gb, 5);
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if (get_bits(&gb, 1))
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continue;
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skip_bits_long(&gb, 9);
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lfe = get_bits(&gb, 2);
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if (lfe > 2)
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continue;
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marker += 4* sr_code;
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markers[marker] ++;
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}
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sum = max = 0;
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for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
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sum += markers[i];
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if (markers[max] < markers[i])
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max = i;
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}
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if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
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markers[max] * 4 > sum * 3 &&
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diff / p->buf_size > 200)
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return AVPROBE_SCORE_EXTENSION + 1;
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return 0;
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}
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AVInputFormat ff_dts_demuxer = {
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.name = "dts",
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.long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
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.read_probe = dts_probe,
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.read_header = ff_raw_audio_read_header,
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.read_packet = ff_raw_read_partial_packet,
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.flags = AVFMT_GENERIC_INDEX,
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.extensions = "dts",
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.raw_codec_id = AV_CODEC_ID_DTS,
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};
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