236 lines
7.2 KiB
C
236 lines
7.2 KiB
C
/*
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* IEC 61937 demuxer
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* Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
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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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/**
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* @file
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* IEC 61937 demuxer, used for compressed data in S/PDIF
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* @author Anssi Hannula
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*/
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#include "avformat.h"
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#include "spdif.h"
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#include "libavcodec/ac3.h"
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#include "libavcodec/aacadtsdec.h"
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static int spdif_get_offset_and_codec(AVFormatContext *s,
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enum IEC61937DataType data_type,
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const char *buf, int *offset,
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enum CodecID *codec)
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{
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AACADTSHeaderInfo aac_hdr;
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GetBitContext gbc;
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switch (data_type & 0xff) {
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case IEC61937_AC3:
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*offset = AC3_FRAME_SIZE << 2;
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*codec = CODEC_ID_AC3;
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break;
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case IEC61937_MPEG1_LAYER1:
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*offset = spdif_mpeg_pkt_offset[1][0];
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*codec = CODEC_ID_MP1;
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break;
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case IEC61937_MPEG1_LAYER23:
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*offset = spdif_mpeg_pkt_offset[1][0];
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*codec = CODEC_ID_MP3;
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break;
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case IEC61937_MPEG2_EXT:
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*offset = 4608;
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*codec = CODEC_ID_MP3;
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break;
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case IEC61937_MPEG2_AAC:
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init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8);
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if (avpriv_aac_parse_header(&gbc, &aac_hdr)) {
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if (s) /* be silent during a probe */
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av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
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return AVERROR_INVALIDDATA;
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}
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*offset = aac_hdr.samples << 2;
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*codec = CODEC_ID_AAC;
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break;
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case IEC61937_MPEG2_LAYER1_LSF:
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*offset = spdif_mpeg_pkt_offset[0][0];
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*codec = CODEC_ID_MP1;
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break;
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case IEC61937_MPEG2_LAYER2_LSF:
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*offset = spdif_mpeg_pkt_offset[0][1];
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*codec = CODEC_ID_MP2;
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break;
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case IEC61937_MPEG2_LAYER3_LSF:
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*offset = spdif_mpeg_pkt_offset[0][2];
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*codec = CODEC_ID_MP3;
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break;
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case IEC61937_DTS1:
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*offset = 2048;
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*codec = CODEC_ID_DTS;
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break;
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case IEC61937_DTS2:
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*offset = 4096;
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*codec = CODEC_ID_DTS;
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break;
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case IEC61937_DTS3:
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*offset = 8192;
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*codec = CODEC_ID_DTS;
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break;
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default:
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if (s) { /* be silent during a probe */
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av_log(s, AV_LOG_WARNING, "Data type 0x%04x", data_type);
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av_log_missing_feature(s, " in IEC 61937 is", 1);
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}
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return AVERROR_PATCHWELCOME;
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}
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return 0;
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}
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/* Largest offset between bursts we currently handle, i.e. AAC with
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aac_hdr.samples = 4096 */
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#define SPDIF_MAX_OFFSET 16384
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static int spdif_probe(AVProbeData *p)
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{
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const uint8_t *buf = p->buf;
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const uint8_t *probe_end = p->buf + FFMIN(2 * SPDIF_MAX_OFFSET, p->buf_size - 1);
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const uint8_t *expected_code = buf + 7;
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uint32_t state = 0;
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int sync_codes = 0;
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int consecutive_codes = 0;
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int offset;
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enum CodecID codec;
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for (; buf < probe_end; buf++) {
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state = (state << 8) | *buf;
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if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
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&& buf[1] < 0x37) {
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sync_codes++;
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if (buf == expected_code) {
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if (++consecutive_codes >= 2)
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return AVPROBE_SCORE_MAX;
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} else
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consecutive_codes = 0;
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if (buf + 4 + AAC_ADTS_HEADER_SIZE > p->buf + p->buf_size)
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break;
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/* continue probing to find more sync codes */
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probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p->buf + p->buf_size - 1);
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/* skip directly to the next sync code */
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if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
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&buf[5], &offset, &codec)) {
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if (buf + offset >= p->buf + p->buf_size)
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break;
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expected_code = buf + offset;
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buf = expected_code - 7;
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}
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}
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}
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if (!sync_codes)
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return 0;
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if (sync_codes >= 6)
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/* good amount of sync codes but with unexpected offsets */
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return AVPROBE_SCORE_MAX / 2;
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/* some sync codes were found */
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return AVPROBE_SCORE_MAX / 8;
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}
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static int spdif_read_header(AVFormatContext *s)
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{
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s->ctx_flags |= AVFMTCTX_NOHEADER;
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return 0;
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}
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static int spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVIOContext *pb = s->pb;
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enum IEC61937DataType data_type;
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enum CodecID codec_id;
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uint32_t state = 0;
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int pkt_size_bits, offset, ret;
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while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
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state = (state << 8) | avio_r8(pb);
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if (pb->eof_reached)
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return AVERROR_EOF;
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}
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data_type = avio_rl16(pb);
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pkt_size_bits = avio_rl16(pb);
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if (pkt_size_bits % 16)
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av_log_ask_for_sample(s, "Packet does not end to a 16-bit boundary.");
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ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
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if (ret)
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return ret;
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pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
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if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
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av_free_packet(pkt);
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return AVERROR_EOF;
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}
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ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
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ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
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&offset, &codec_id);
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if (ret) {
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av_free_packet(pkt);
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return ret;
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}
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/* skip over the padding to the beginning of the next frame */
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avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
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if (!s->nb_streams) {
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/* first packet, create a stream */
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AVStream *st = avformat_new_stream(s, NULL);
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if (!st) {
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av_free_packet(pkt);
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return AVERROR(ENOMEM);
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}
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st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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st->codec->codec_id = codec_id;
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} else if (codec_id != s->streams[0]->codec->codec_id) {
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av_log_missing_feature(s, "codec change in IEC 61937", 0);
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return AVERROR_PATCHWELCOME;
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}
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if (!s->bit_rate && s->streams[0]->codec->sample_rate)
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/* stream bitrate matches 16-bit stereo PCM bitrate for currently
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supported codecs */
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s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate;
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return 0;
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}
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AVInputFormat ff_spdif_demuxer = {
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.name = "spdif",
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.long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
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.read_probe = spdif_probe,
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.read_header = spdif_read_header,
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.read_packet = spdif_read_packet,
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.flags = AVFMT_GENERIC_INDEX,
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};
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