diff options
Diffstat (limited to 'ffmpeg1/libavformat/westwood_aud.c')
| -rw-r--r-- | ffmpeg1/libavformat/westwood_aud.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/ffmpeg1/libavformat/westwood_aud.c b/ffmpeg1/libavformat/westwood_aud.c new file mode 100644 index 0000000..d666117 --- /dev/null +++ b/ffmpeg1/libavformat/westwood_aud.c @@ -0,0 +1,181 @@ +/* + * Westwood Studios AUD Format Demuxer + * Copyright (c) 2003 The ffmpeg Project + * + * 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 + * Westwood Studios AUD file demuxer + * by Mike Melanson (melanson@pcisys.net) + * for more information on the Westwood file formats, visit: + * http://www.pcisys.net/~melanson/codecs/ + * http://www.geocities.com/SiliconValley/8682/aud3.txt + * + * Implementation note: There is no definite file signature for AUD files. + * The demuxer uses a probabilistic strategy for content detection. This + * entails performing sanity checks on certain header values in order to + * qualify a file. Refer to wsaud_probe() for the precise parameters. + */ + +#include "libavutil/channel_layout.h" +#include "libavutil/intreadwrite.h" +#include "avformat.h" +#include "internal.h" + +#define AUD_HEADER_SIZE 12 +#define AUD_CHUNK_PREAMBLE_SIZE 8 +#define AUD_CHUNK_SIGNATURE 0x0000DEAF + +static int wsaud_probe(AVProbeData *p) +{ + int field; + + /* Probabilistic content detection strategy: There is no file signature + * so perform sanity checks on various header parameters: + * 8000 <= sample rate (16 bits) <= 48000 ==> 40001 acceptable numbers + * flags <= 0x03 (2 LSBs are used) ==> 4 acceptable numbers + * compression type (8 bits) = 1 or 99 ==> 2 acceptable numbers + * first audio chunk signature (32 bits) ==> 1 acceptable number + * The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 = + * 320008 acceptable number combinations. + */ + + if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE) + return 0; + + /* check sample rate */ + field = AV_RL16(&p->buf[0]); + if ((field < 8000) || (field > 48000)) + return 0; + + /* enforce the rule that the top 6 bits of this flags field are reserved (0); + * this might not be true, but enforce it until deemed unnecessary */ + if (p->buf[10] & 0xFC) + return 0; + + if (p->buf[11] != 99 && p->buf[11] != 1) + return 0; + + /* read ahead to the first audio chunk and validate the first header signature */ + if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE) + return 0; + + /* return 1/2 certainty since this file check is a little sketchy */ + return AVPROBE_SCORE_MAX / 2; +} + +static int wsaud_read_header(AVFormatContext *s) +{ + AVIOContext *pb = s->pb; + AVStream *st; + unsigned char header[AUD_HEADER_SIZE]; + int sample_rate, channels, codec; + + if (avio_read(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE) + return AVERROR(EIO); + + sample_rate = AV_RL16(&header[0]); + channels = (header[10] & 0x1) + 1; + codec = header[11]; + + /* initialize the audio decoder stream */ + st = avformat_new_stream(s, NULL); + if (!st) + return AVERROR(ENOMEM); + + switch (codec) { + case 1: + if (channels != 1) { + avpriv_request_sample(s, "Stereo WS-SND1"); + return AVERROR_PATCHWELCOME; + } + st->codec->codec_id = AV_CODEC_ID_WESTWOOD_SND1; + break; + case 99: + st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_WS; + st->codec->bits_per_coded_sample = 4; + st->codec->bit_rate = channels * sample_rate * 4; + break; + default: + avpriv_request_sample(s, "Unknown codec: %d", codec); + return AVERROR_PATCHWELCOME; + } + avpriv_set_pts_info(st, 64, 1, sample_rate); + st->codec->codec_type = AVMEDIA_TYPE_AUDIO; + st->codec->channels = channels; + st->codec->channel_layout = channels == 1 ? AV_CH_LAYOUT_MONO : + AV_CH_LAYOUT_STEREO; + st->codec->sample_rate = sample_rate; + + return 0; +} + +static int wsaud_read_packet(AVFormatContext *s, + AVPacket *pkt) +{ + AVIOContext *pb = s->pb; + unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE]; + unsigned int chunk_size; + int ret = 0; + AVStream *st = s->streams[0]; + + if (avio_read(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) != + AUD_CHUNK_PREAMBLE_SIZE) + return AVERROR(EIO); + + /* validate the chunk */ + if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE) + return AVERROR_INVALIDDATA; + + chunk_size = AV_RL16(&preamble[0]); + + if (st->codec->codec_id == AV_CODEC_ID_WESTWOOD_SND1) { + /* For Westwood SND1 audio we need to add the output size and input + size to the start of the packet to match what is in VQA. + Specifically, this is needed to signal when a packet should be + decoding as raw 8-bit pcm or variable-size ADPCM. */ + int out_size = AV_RL16(&preamble[2]); + if ((ret = av_new_packet(pkt, chunk_size + 4))) + return ret; + if ((ret = avio_read(pb, &pkt->data[4], chunk_size)) != chunk_size) + return ret < 0 ? ret : AVERROR(EIO); + AV_WL16(&pkt->data[0], out_size); + AV_WL16(&pkt->data[2], chunk_size); + + pkt->duration = out_size; + } else { + ret = av_get_packet(pb, pkt, chunk_size); + if (ret != chunk_size) + return AVERROR(EIO); + + /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */ + pkt->duration = (chunk_size * 2) / st->codec->channels; + } + pkt->stream_index = st->index; + + return ret; +} + +AVInputFormat ff_wsaud_demuxer = { + .name = "wsaud", + .long_name = NULL_IF_CONFIG_SMALL("Westwood Studios audio"), + .read_probe = wsaud_probe, + .read_header = wsaud_read_header, + .read_packet = wsaud_read_packet, +}; |