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 #include "avformat.h"
00024 
00025 static int apc_probe(AVProbeData *p)
00026 {
00027     if (!strncmp(p->buf, "CRYO_APC", 8))
00028         return AVPROBE_SCORE_MAX;
00029 
00030     return 0;
00031 }
00032 
00033 static int apc_read_header(AVFormatContext *s)
00034 {
00035     AVIOContext *pb = s->pb;
00036     AVStream *st;
00037 
00038     avio_rl32(pb); /* CRYO */
00039     avio_rl32(pb); /* _APC */
00040     avio_rl32(pb); /* 1.20 */
00041 
00042     st = avformat_new_stream(s, NULL);
00043     if (!st)
00044         return AVERROR(ENOMEM);
00045 
00046     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00047     st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
00048 
00049     avio_rl32(pb); /* number of samples */
00050     st->codec->sample_rate = avio_rl32(pb);
00051 
00052     st->codec->extradata_size = 2 * 4;
00053     st->codec->extradata = av_malloc(st->codec->extradata_size +
00054                                      FF_INPUT_BUFFER_PADDING_SIZE);
00055     if (!st->codec->extradata)
00056         return AVERROR(ENOMEM);
00057 
00058     /* initial predictor values for adpcm decoder */
00059     avio_read(pb, st->codec->extradata, 2 * 4);
00060 
00061     st->codec->channels = 1;
00062     if (avio_rl32(pb))
00063         st->codec->channels = 2;
00064 
00065     st->codec->bits_per_coded_sample = 4;
00066     st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels
00067                           * st->codec->sample_rate;
00068     st->codec->block_align = 1;
00069 
00070     return 0;
00071 }
00072 
00073 #define MAX_READ_SIZE 4096
00074 
00075 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
00076 {
00077     if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
00078         return AVERROR(EIO);
00079     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
00080     pkt->stream_index = 0;
00081     return 0;
00082 }
00083 
00084 AVInputFormat ff_apc_demuxer = {
00085     .name           = "apc",
00086     .long_name      = NULL_IF_CONFIG_SMALL("CRYO APC"),
00087     .read_probe     = apc_probe,
00088     .read_header    = apc_read_header,
00089     .read_packet    = apc_read_packet,
00090 };