The only parameters needed by the demuxers are the sample rate and sample count, which can be trivially extracted manually, without resorting to an avpriv function.
		
			
				
	
	
		
			195 lines
		
	
	
		
			7.1 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			195 lines
		
	
	
		
			7.1 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * Raw FLAC demuxer
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 * Copyright (c) 2001 Fabrice Bellard
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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/flac.h"
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#include "avformat.h"
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#include "flac_picture.h"
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#include "internal.h"
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#include "rawdec.h"
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#include "oggdec.h"
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#include "vorbiscomment.h"
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#include "replaygain.h"
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static int flac_read_header(AVFormatContext *s)
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{
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    int ret, metadata_last=0, metadata_type, metadata_size, found_streaminfo=0;
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    uint8_t header[4];
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    uint8_t *buffer=NULL;
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    AVStream *st = avformat_new_stream(s, NULL);
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    if (!st)
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        return AVERROR(ENOMEM);
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    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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    st->codec->codec_id = AV_CODEC_ID_FLAC;
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    st->need_parsing = AVSTREAM_PARSE_FULL;
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    /* the parameters will be extracted from the compressed bitstream */
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    /* if fLaC marker is not found, assume there is no header */
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    if (avio_rl32(s->pb) != MKTAG('f','L','a','C')) {
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        avio_seek(s->pb, -4, SEEK_CUR);
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        return 0;
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    }
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    /* process metadata blocks */
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    while (!s->pb->eof_reached && !metadata_last) {
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        avio_read(s->pb, header, 4);
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        flac_parse_block_header(header, &metadata_last, &metadata_type,
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                                   &metadata_size);
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        switch (metadata_type) {
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        /* allocate and read metadata block for supported types */
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        case FLAC_METADATA_TYPE_STREAMINFO:
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        case FLAC_METADATA_TYPE_CUESHEET:
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        case FLAC_METADATA_TYPE_PICTURE:
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        case FLAC_METADATA_TYPE_VORBIS_COMMENT:
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            buffer = av_mallocz(metadata_size + FF_INPUT_BUFFER_PADDING_SIZE);
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            if (!buffer) {
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                return AVERROR(ENOMEM);
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            }
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            if (avio_read(s->pb, buffer, metadata_size) != metadata_size) {
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                av_freep(&buffer);
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                return AVERROR(EIO);
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            }
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            break;
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        /* skip metadata block for unsupported types */
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        default:
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            ret = avio_skip(s->pb, metadata_size);
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            if (ret < 0)
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                return ret;
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        }
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        if (metadata_type == FLAC_METADATA_TYPE_STREAMINFO) {
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            uint32_t samplerate;
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            uint64_t samples;
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            /* STREAMINFO can only occur once */
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            if (found_streaminfo) {
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                av_freep(&buffer);
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                return AVERROR_INVALIDDATA;
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            }
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            if (metadata_size != FLAC_STREAMINFO_SIZE) {
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                av_freep(&buffer);
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                return AVERROR_INVALIDDATA;
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            }
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            found_streaminfo = 1;
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            st->codec->extradata      = buffer;
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            st->codec->extradata_size = metadata_size;
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            buffer = NULL;
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            /* get sample rate and sample count from STREAMINFO header;
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             * other parameters will be extracted by the parser */
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            samplerate = AV_RB24(st->codec->extradata + 10) >> 4;
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            samples    = (AV_RB64(st->codec->extradata + 13) >> 24) & ((1ULL << 36) - 1);
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            /* set time base and duration */
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            if (samplerate > 0) {
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                avpriv_set_pts_info(st, 64, 1, samplerate);
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                if (samples > 0)
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                    st->duration = samples;
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            }
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        } else if (metadata_type == FLAC_METADATA_TYPE_CUESHEET) {
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            uint8_t isrc[13];
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            uint64_t start;
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            const uint8_t *offset;
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            int i, chapters, track, ti;
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            if (metadata_size < 431)
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                return AVERROR_INVALIDDATA;
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            offset = buffer + 395;
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            chapters = bytestream_get_byte(&offset) - 1;
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            if (chapters <= 0)
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                return AVERROR_INVALIDDATA;
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            for (i = 0; i < chapters; i++) {
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                if (offset + 36 - buffer > metadata_size)
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                    return AVERROR_INVALIDDATA;
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                start = bytestream_get_be64(&offset);
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                track = bytestream_get_byte(&offset);
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                bytestream_get_buffer(&offset, isrc, 12);
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                isrc[12] = 0;
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                offset += 14;
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                ti = bytestream_get_byte(&offset);
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                if (ti <= 0) return AVERROR_INVALIDDATA;
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                offset += ti * 12;
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                avpriv_new_chapter(s, track, st->time_base, start, AV_NOPTS_VALUE, isrc);
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            }
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        } else if (metadata_type == FLAC_METADATA_TYPE_PICTURE) {
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            ret = ff_flac_parse_picture(s, buffer, metadata_size);
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            av_freep(&buffer);
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            if (ret < 0) {
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                av_log(s, AV_LOG_ERROR, "Error parsing attached picture.\n");
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                return ret;
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            }
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        } else {
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            /* STREAMINFO must be the first block */
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            if (!found_streaminfo) {
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                av_freep(&buffer);
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                return AVERROR_INVALIDDATA;
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            }
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            /* process supported blocks other than STREAMINFO */
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            if (metadata_type == FLAC_METADATA_TYPE_VORBIS_COMMENT) {
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                AVDictionaryEntry *chmask;
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                ret = ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1);
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                if (ret < 0) {
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                    av_log(s, AV_LOG_WARNING, "error parsing VorbisComment metadata\n");
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                } else if (ret > 0) {
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                    s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
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                }
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                /* parse the channels mask if present */
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                chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);
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                if (chmask) {
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                    uint64_t mask = strtol(chmask->value, NULL, 0);
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                    if (!mask || mask & ~0x3ffffULL) {
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                        av_log(s, AV_LOG_WARNING,
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                               "Invalid value of WAVEFORMATEXTENSIBLE_CHANNEL_MASK\n");
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                    } else {
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                        st->codec->channel_layout = mask;
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                        av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);
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                    }
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                }
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            }
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            av_freep(&buffer);
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        }
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    }
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    ret = ff_replaygain_export(st, s->metadata);
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    if (ret < 0)
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        return ret;
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    return 0;
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}
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static int flac_probe(AVProbeData *p)
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{
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    if (p->buf_size < 4 || memcmp(p->buf, "fLaC", 4))
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        return 0;
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    return AVPROBE_SCORE_EXTENSION;
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}
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AVInputFormat ff_flac_demuxer = {
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    .name           = "flac",
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    .long_name      = NULL_IF_CONFIG_SMALL("raw FLAC"),
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    .read_probe     = flac_probe,
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    .read_header    = flac_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     = "flac",
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    .raw_codec_id   = AV_CODEC_ID_FLAC,
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};
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