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128 lines
3.7 KiB
128 lines
3.7 KiB
/* |
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* Maxis XA (.xa) File Demuxer |
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* Copyright (c) 2008 Robert Marston |
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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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* Maxis XA File Demuxer |
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* by Robert Marston (rmarston@gmail.com) |
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* for more information on the XA audio format see |
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* http://wiki.multimedia.cx/index.php?title=Maxis_XA |
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*/ |
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#include "libavutil/intreadwrite.h" |
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#include "avformat.h" |
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#define XA00_TAG MKTAG('X', 'A', 0, 0) |
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#define XAI0_TAG MKTAG('X', 'A', 'I', 0) |
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#define XAJ0_TAG MKTAG('X', 'A', 'J', 0) |
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typedef struct MaxisXADemuxContext { |
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uint32_t out_size; |
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uint32_t sent_bytes; |
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uint32_t audio_frame_counter; |
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} MaxisXADemuxContext; |
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static int xa_probe(AVProbeData *p) |
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{ |
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int channels, srate, bits_per_sample; |
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if (p->buf_size < 24) |
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return 0; |
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switch(AV_RL32(p->buf)) { |
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case XA00_TAG: |
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case XAI0_TAG: |
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case XAJ0_TAG: |
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break; |
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default: |
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return 0; |
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} |
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channels = AV_RL16(p->buf + 10); |
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srate = AV_RL32(p->buf + 12); |
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bits_per_sample = AV_RL16(p->buf + 22); |
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if (!channels || channels > 8 || !srate || srate > 192000 || |
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bits_per_sample < 4 || bits_per_sample > 32) |
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return 0; |
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return AVPROBE_SCORE_MAX/2; |
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} |
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static int xa_read_header(AVFormatContext *s, |
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AVFormatParameters *ap) |
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{ |
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MaxisXADemuxContext *xa = s->priv_data; |
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ByteIOContext *pb = s->pb; |
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AVStream *st; |
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/*Set up the XA Audio Decoder*/ |
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st = av_new_stream(s, 0); |
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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 = CODEC_ID_ADPCM_EA_MAXIS_XA; |
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url_fskip(pb, 4); /* Skip the XA ID */ |
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xa->out_size = get_le32(pb); |
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url_fskip(pb, 2); /* Skip the tag */ |
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st->codec->channels = get_le16(pb); |
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st->codec->sample_rate = get_le32(pb); |
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/* Value in file is average byte rate*/ |
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st->codec->bit_rate = get_le32(pb) * 8; |
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st->codec->block_align = get_le16(pb); |
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st->codec->bits_per_coded_sample = get_le16(pb); |
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av_set_pts_info(st, 64, 1, st->codec->sample_rate); |
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return 0; |
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} |
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static int xa_read_packet(AVFormatContext *s, |
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AVPacket *pkt) |
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{ |
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MaxisXADemuxContext *xa = s->priv_data; |
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AVStream *st = s->streams[0]; |
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ByteIOContext *pb = s->pb; |
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unsigned int packet_size; |
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int ret; |
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if(xa->sent_bytes > xa->out_size) |
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return AVERROR(EIO); |
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/* 1 byte header and 14 bytes worth of samples * number channels per block */ |
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packet_size = 15*st->codec->channels; |
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ret = av_get_packet(pb, pkt, packet_size); |
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if(ret < 0) |
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return ret; |
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pkt->stream_index = st->index; |
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xa->sent_bytes += packet_size; |
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pkt->pts = xa->audio_frame_counter; |
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/* 14 bytes Samples per channel with 2 samples per byte */ |
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xa->audio_frame_counter += 28 * st->codec->channels; |
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return ret; |
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} |
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AVInputFormat ff_xa_demuxer = { |
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"xa", |
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NULL_IF_CONFIG_SMALL("Maxis XA File Format"), |
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sizeof(MaxisXADemuxContext), |
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xa_probe, |
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xa_read_header, |
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xa_read_packet, |
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};
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