| /* |
| * Maxis XA (.xa) File Demuxer |
| * Copyright (c) 2008 Robert Marston |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file libavformat/xa.c |
| * Maxis XA File Demuxer |
| * by Robert Marston (rmarston@gmail.com) |
| * for more information on the XA audio format see |
| * http://wiki.multimedia.cx/index.php?title=Maxis_XA |
| */ |
| |
| #include "libavutil/intreadwrite.h" |
| #include "avformat.h" |
| |
| #define XA00_TAG MKTAG('X', 'A', 0, 0) |
| #define XAI0_TAG MKTAG('X', 'A', 'I', 0) |
| #define XAJ0_TAG MKTAG('X', 'A', 'J', 0) |
| |
| typedef struct MaxisXADemuxContext { |
| uint32_t out_size; |
| uint32_t sent_bytes; |
| uint32_t audio_frame_counter; |
| } MaxisXADemuxContext; |
| |
| static int xa_probe(AVProbeData *p) |
| { |
| switch(AV_RL32(p->buf)) { |
| case XA00_TAG: |
| case XAI0_TAG: |
| case XAJ0_TAG: |
| return AVPROBE_SCORE_MAX; |
| } |
| return 0; |
| } |
| |
| static int xa_read_header(AVFormatContext *s, |
| AVFormatParameters *ap) |
| { |
| MaxisXADemuxContext *xa = s->priv_data; |
| ByteIOContext *pb = s->pb; |
| AVStream *st; |
| |
| /*Set up the XA Audio Decoder*/ |
| st = av_new_stream(s, 0); |
| if (!st) |
| return AVERROR(ENOMEM); |
| |
| st->codec->codec_type = CODEC_TYPE_AUDIO; |
| st->codec->codec_id = CODEC_ID_ADPCM_EA_MAXIS_XA; |
| url_fskip(pb, 4); /* Skip the XA ID */ |
| xa->out_size = get_le32(pb); |
| url_fskip(pb, 2); /* Skip the tag */ |
| st->codec->channels = get_le16(pb); |
| st->codec->sample_rate = get_le32(pb); |
| /* Value in file is average byte rate*/ |
| st->codec->bit_rate = get_le32(pb) * 8; |
| st->codec->block_align = get_le16(pb); |
| st->codec->bits_per_coded_sample = get_le16(pb); |
| |
| av_set_pts_info(st, 64, 1, st->codec->sample_rate); |
| |
| return 0; |
| } |
| |
| static int xa_read_packet(AVFormatContext *s, |
| AVPacket *pkt) |
| { |
| MaxisXADemuxContext *xa = s->priv_data; |
| AVStream *st = s->streams[0]; |
| ByteIOContext *pb = s->pb; |
| unsigned int packet_size; |
| int ret; |
| |
| if(xa->sent_bytes > xa->out_size) |
| return AVERROR(EIO); |
| /* 1 byte header and 14 bytes worth of samples * number channels per block */ |
| packet_size = 15*st->codec->channels; |
| |
| ret = av_get_packet(pb, pkt, packet_size); |
| if(ret != packet_size) |
| return AVERROR(EIO); |
| |
| pkt->stream_index = st->index; |
| xa->sent_bytes += packet_size; |
| pkt->pts = xa->audio_frame_counter; |
| /* 14 bytes Samples per channel with 2 samples per byte */ |
| xa->audio_frame_counter += 28 * st->codec->channels; |
| |
| return ret; |
| } |
| |
| AVInputFormat xa_demuxer = { |
| "xa", |
| NULL_IF_CONFIG_SMALL("Maxis XA File Format"), |
| sizeof(MaxisXADemuxContext), |
| xa_probe, |
| xa_read_header, |
| xa_read_packet, |
| }; |