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https://git.ffmpeg.org/ffmpeg.git
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bec2ce0f71
Port every caller to the new entry point, which lets libavcodec allocate the header, and prepare the old one for removal. The mp3 decoder keeps a named MPADecodeHeader2 in its context, so the macro spelling out the header fields is no longer needed.
148 lines
4.5 KiB
C
148 lines
4.5 KiB
C
/*
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* MPEG Audio header decoder
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* Copyright (c) 2001, 2002 Fabrice Bellard
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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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* MPEG Audio header decoder.
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*/
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#ifndef AVCODEC_MPEGAUDIODECHEADER_H
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#define AVCODEC_MPEGAUDIODECHEADER_H
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#include <stdint.h>
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#include "libavutil/attributes.h"
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#include "codec_id.h"
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#include "version_major.h"
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#define MP3_MASK 0xFFFE0CCF
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#define FF_MPEGAUDIO_LEGACY_DECODE_HEADER (LIBAVCODEC_VERSION_MAJOR < 64)
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#if FF_MPEGAUDIO_LEGACY_DECODE_HEADER
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#define MPA_DECODE_HEADER \
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int frame_size; \
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int error_protection; \
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int layer; \
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int sample_rate; \
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int sample_rate_index; /* between 0 and 8 */ \
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int bit_rate; \
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int nb_channels; \
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int mode; \
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int mode_ext; \
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int lsf;
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typedef struct MPADecodeHeader {
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MPA_DECODE_HEADER
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} MPADecodeHeader;
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/* header decoding. MUST check the header before because no
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consistency check is done there. Return 1 if free format found and
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that the frame size must be computed externally */
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int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header);
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#endif
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/**
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* Same as MPADecodeHeader, plus the header fields that carry no decoding
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* information. Its size is not part of the libavcodec ABI: it is only ever
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* allocated by avpriv_mpegaudio_decode_header2().
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*/
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typedef struct MPADecodeHeader2 {
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int frame_size;
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int error_protection;
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int layer;
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int sample_rate;
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int sample_rate_index; /* between 0 and 8 */
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int bit_rate;
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int nb_channels;
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int mode;
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int mode_ext;
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int lsf;
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int copyright;
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int original;
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int emphasis;
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int bitrate_index;
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int padding;
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int private_bit;
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} MPADecodeHeader2;
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/**
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* Decode an MPEG audio header into *phdr, which is allocated if it is NULL.
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*
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* The header must have been checked beforehand, as no consistency check is
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* done here.
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*
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* @return 1 if free format was found and the frame size must be computed
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* externally, 0 on success, a negative AVERROR code on failure
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*/
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int avpriv_mpegaudio_decode_header2(MPADecodeHeader2 **phdr, uint32_t header);
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/* same as avpriv_mpegaudio_decode_header2(), for callers within libavcodec,
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which are built against this very header and may allocate it themselves */
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int ff_mpegaudio_decode_header(MPADecodeHeader2 *s, uint32_t header);
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/* useful helper to get MPEG audio stream info. Return -1 if error in
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header, otherwise the coded frame size in bytes */
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int ff_mpa_decode_header(uint32_t head, int *sample_rate,
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int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id);
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/* fast header check for resync */
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static inline int ff_mpa_check_header(uint32_t header){
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/* header */
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if ((header & 0xffe00000) != 0xffe00000)
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return -1;
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/* version check */
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if ((header & (3<<19)) == 1<<19)
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return -1;
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/* layer check */
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if ((header & (3<<17)) == 0)
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return -1;
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/* bit rate */
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if ((header & (0xf<<12)) == 0xf<<12)
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return -1;
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/* frequency */
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if ((header & (3<<10)) == 3<<10)
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return -1;
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return 0;
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}
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static inline uint32_t ff_mpa_encode_header(const MPADecodeHeader2 *s)
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{
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int version = s->sample_rate_index < 6 ? 3 - s->sample_rate_index / 3 : 0;
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return 0xffeU << 20 |
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version << 19 |
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(4 - s->layer) << 17 |
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!s->error_protection << 16 |
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s->bitrate_index << 12 |
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s->sample_rate_index % 3 << 10 |
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s->padding << 9 |
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s->private_bit << 8 |
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s->mode << 6 |
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s->mode_ext << 4 |
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s->copyright << 3 |
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s->original << 2 |
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s->emphasis;
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}
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#endif /* AVCODEC_MPEGAUDIODECHEADER_H */
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