| 1 | /* |
| 2 | * Maxis XA (.xa) File Demuxer |
| 3 | * Copyright (c) 2008 Robert Marston |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | /** |
| 23 | * @file |
| 24 | * Maxis XA File Demuxer |
| 25 | * by Robert Marston (rmarston@gmail.com) |
| 26 | * for more information on the XA audio format see |
| 27 | * http://wiki.multimedia.cx/index.php?title=Maxis_XA |
| 28 | */ |
| 29 | |
| 30 | #include "libavutil/intreadwrite.h" |
| 31 | #include "avformat.h" |
| 32 | #include "internal.h" |
| 33 | |
| 34 | #define XA00_TAG MKTAG('X', 'A', 0, 0) |
| 35 | #define XAI0_TAG MKTAG('X', 'A', 'I', 0) |
| 36 | #define XAJ0_TAG MKTAG('X', 'A', 'J', 0) |
| 37 | |
| 38 | typedef struct MaxisXADemuxContext { |
| 39 | uint32_t out_size; |
| 40 | uint32_t sent_bytes; |
| 41 | } MaxisXADemuxContext; |
| 42 | |
| 43 | static int xa_probe(AVProbeData *p) |
| 44 | { |
| 45 | int channels, srate, bits_per_sample; |
| 46 | if (p->buf_size < 24) |
| 47 | return 0; |
| 48 | switch(AV_RL32(p->buf)) { |
| 49 | case XA00_TAG: |
| 50 | case XAI0_TAG: |
| 51 | case XAJ0_TAG: |
| 52 | break; |
| 53 | default: |
| 54 | return 0; |
| 55 | } |
| 56 | channels = AV_RL16(p->buf + 10); |
| 57 | srate = AV_RL32(p->buf + 12); |
| 58 | bits_per_sample = AV_RL16(p->buf + 22); |
| 59 | if (!channels || channels > 8 || !srate || srate > 192000 || |
| 60 | bits_per_sample < 4 || bits_per_sample > 32) |
| 61 | return 0; |
| 62 | return AVPROBE_SCORE_EXTENSION; |
| 63 | } |
| 64 | |
| 65 | static int xa_read_header(AVFormatContext *s) |
| 66 | { |
| 67 | MaxisXADemuxContext *xa = s->priv_data; |
| 68 | AVIOContext *pb = s->pb; |
| 69 | AVStream *st; |
| 70 | |
| 71 | /*Set up the XA Audio Decoder*/ |
| 72 | st = avformat_new_stream(s, NULL); |
| 73 | if (!st) |
| 74 | return AVERROR(ENOMEM); |
| 75 | |
| 76 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; |
| 77 | st->codec->codec_id = AV_CODEC_ID_ADPCM_EA_MAXIS_XA; |
| 78 | avio_skip(pb, 4); /* Skip the XA ID */ |
| 79 | xa->out_size = avio_rl32(pb); |
| 80 | avio_skip(pb, 2); /* Skip the tag */ |
| 81 | st->codec->channels = avio_rl16(pb); |
| 82 | st->codec->sample_rate = avio_rl32(pb); |
| 83 | avio_skip(pb, 4); /* Skip average byte rate */ |
| 84 | avio_skip(pb, 2); /* Skip block align */ |
| 85 | avio_skip(pb, 2); /* Skip bits-per-sample */ |
| 86 | |
| 87 | if (!st->codec->channels || !st->codec->sample_rate) |
| 88 | return AVERROR_INVALIDDATA; |
| 89 | |
| 90 | st->codec->bit_rate = av_clip(15LL * st->codec->channels * 8 * |
| 91 | st->codec->sample_rate / 28, 0, INT_MAX); |
| 92 | |
| 93 | avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate); |
| 94 | st->start_time = 0; |
| 95 | |
| 96 | return 0; |
| 97 | } |
| 98 | |
| 99 | static int xa_read_packet(AVFormatContext *s, |
| 100 | AVPacket *pkt) |
| 101 | { |
| 102 | MaxisXADemuxContext *xa = s->priv_data; |
| 103 | AVStream *st = s->streams[0]; |
| 104 | AVIOContext *pb = s->pb; |
| 105 | unsigned int packet_size; |
| 106 | int ret; |
| 107 | |
| 108 | if (xa->sent_bytes >= xa->out_size) |
| 109 | return AVERROR_EOF; |
| 110 | /* 1 byte header and 14 bytes worth of samples * number channels per block */ |
| 111 | packet_size = 15*st->codec->channels; |
| 112 | |
| 113 | ret = av_get_packet(pb, pkt, packet_size); |
| 114 | if(ret < 0) |
| 115 | return ret; |
| 116 | |
| 117 | pkt->stream_index = st->index; |
| 118 | xa->sent_bytes += packet_size; |
| 119 | pkt->duration = 28; |
| 120 | |
| 121 | return ret; |
| 122 | } |
| 123 | |
| 124 | AVInputFormat ff_xa_demuxer = { |
| 125 | .name = "xa", |
| 126 | .long_name = NULL_IF_CONFIG_SMALL("Maxis XA"), |
| 127 | .priv_data_size = sizeof(MaxisXADemuxContext), |
| 128 | .read_probe = xa_probe, |
| 129 | .read_header = xa_read_header, |
| 130 | .read_packet = xa_read_packet, |
| 131 | }; |