FFmpeg: libavformat/apc.c Source File

00001 /*
00002  * CRYO APC audio format demuxer
00003  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include <string.h>
00023 
00024 #include "libavutil/channel_layout.h"
00025 #include "avformat.h"
00026 
00027 static int apc_probe(AVProbeData *p)
00028 {
00029     if (!strncmp(p->buf, "CRYO_APC", 8))
00030         return AVPROBE_SCORE_MAX;
00031 
00032     return 0;
00033 }
00034 
00035 static int apc_read_header(AVFormatContext *s)
00036 {
00037     AVIOContext *pb = s->pb;
00038     AVStream *st;
00039 
00040     avio_rl32(pb); /* CRYO */
00041     avio_rl32(pb); /* _APC */
00042     avio_rl32(pb); /* 1.20 */
00043 
00044     st = avformat_new_stream(s, NULL);
00045     if (!st)
00046         return AVERROR(ENOMEM);
00047 
00048     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00049     st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
00050 
00051     avio_rl32(pb); /* number of samples */
00052     st->codec->sample_rate = avio_rl32(pb);
00053 
00054     st->codec->extradata_size = 2 * 4;
00055     st->codec->extradata = av_malloc(st->codec->extradata_size +
00056                                      FF_INPUT_BUFFER_PADDING_SIZE);
00057     if (!st->codec->extradata)
00058         return AVERROR(ENOMEM);
00059 
00060     /* initial predictor values for adpcm decoder */
00061     avio_read(pb, st->codec->extradata, 2 * 4);
00062 
00063     if (avio_rl32(pb)) {
00064         st->codec->channels       = 2;
00065         st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
00066     } else {
00067         st->codec->channels       = 1;
00068         st->codec->channel_layout = AV_CH_LAYOUT_MONO;
00069     }
00070 
00071     st->codec->bits_per_coded_sample = 4;
00072     st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels
00073                           * st->codec->sample_rate;
00074     st->codec->block_align = 1;
00075 
00076     return 0;
00077 }
00078 
00079 #define MAX_READ_SIZE 4096
00080 
00081 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
00082 {
00083     if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
00084         return AVERROR(EIO);
00085     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
00086     pkt->stream_index = 0;
00087     return 0;
00088 }
00089 
00090 AVInputFormat ff_apc_demuxer = {
00091     .name           = "apc",
00092     .long_name      = NULL_IF_CONFIG_SMALL("CRYO APC"),
00093     .read_probe     = apc_probe,
00094     .read_header    = apc_read_header,
00095     .read_packet    = apc_read_packet,
00096 };