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ffmpeg / libavformat / vocdec.c @ d2062ff6

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/*
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 * Creative Voice File demuxer.
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 * Copyright (c) 2006  Aurelien Jacobs <aurel@gnuage.org>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "voc.h"
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static int voc_probe(AVProbeData *p)
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{
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    int version, check;
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    if (memcmp(p->buf, voc_magic, sizeof(voc_magic) - 1))
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        return 0;
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    version = AV_RL16(p->buf + 22);
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    check = AV_RL16(p->buf + 24);
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    if (~version + 0x1234 != check)
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        return 10;
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    return AVPROBE_SCORE_MAX;
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}
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static int voc_read_header(AVFormatContext *s, AVFormatParameters *ap)
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{
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    voc_dec_context_t *voc = s->priv_data;
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    ByteIOContext *pb = &s->pb;
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    int header_size;
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    AVStream *st;
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    url_fskip(pb, 20);
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    header_size = get_le16(pb) - 22;
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    if (header_size != 4) {
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        av_log(s, AV_LOG_ERROR, "unknown header size: %d\n", header_size);
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        return AVERROR(ENOSYS);
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    }
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    url_fskip(pb, header_size);
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    st = av_new_stream(s, 0);
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    if (!st)
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        return AVERROR(ENOMEM);
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    st->codec->codec_type = CODEC_TYPE_AUDIO;
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    voc->remaining_size = 0;
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    return 0;
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}
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int
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voc_get_packet(AVFormatContext *s, AVPacket *pkt, AVStream *st, int max_size)
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{
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    voc_dec_context_t *voc = s->priv_data;
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    AVCodecContext *dec = st->codec;
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    ByteIOContext *pb = &s->pb;
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    voc_type_t type;
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    int size;
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    int sample_rate = 0;
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    int channels = 1;
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    while (!voc->remaining_size) {
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        type = get_byte(pb);
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        if (type == VOC_TYPE_EOF)
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            return AVERROR(EIO);
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        voc->remaining_size = get_le24(pb);
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        max_size -= 4;
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        switch (type) {
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        case VOC_TYPE_VOICE_DATA:
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            dec->sample_rate = 1000000 / (256 - get_byte(pb));
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            if (sample_rate)
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                dec->sample_rate = sample_rate;
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            dec->channels = channels;
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            dec->codec_id = codec_get_id(voc_codec_tags, get_byte(pb));
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            dec->bits_per_sample = av_get_bits_per_sample(dec->codec_id);
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            voc->remaining_size -= 2;
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            max_size -= 2;
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            channels = 1;
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            break;
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        case VOC_TYPE_VOICE_DATA_CONT:
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            break;
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        case VOC_TYPE_EXTENDED:
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            sample_rate = get_le16(pb);
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            get_byte(pb);
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            channels = get_byte(pb) + 1;
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            sample_rate = 256000000 / (channels * (65536 - sample_rate));
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            voc->remaining_size = 0;
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            max_size -= 4;
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            break;
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        case VOC_TYPE_NEW_VOICE_DATA:
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            dec->sample_rate = get_le32(pb);
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            dec->bits_per_sample = get_byte(pb);
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            dec->channels = get_byte(pb);
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            dec->codec_id = codec_get_id(voc_codec_tags, get_le16(pb));
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            url_fskip(pb, 4);
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            voc->remaining_size -= 12;
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            max_size -= 12;
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            break;
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        default:
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            url_fskip(pb, voc->remaining_size);
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            max_size -= voc->remaining_size;
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            voc->remaining_size = 0;
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            break;
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        }
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    }
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    dec->bit_rate = dec->sample_rate * dec->bits_per_sample;
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    if (max_size <= 0)
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        max_size = 2048;
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    size = FFMIN(voc->remaining_size, max_size);
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    voc->remaining_size -= size;
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    return av_get_packet(pb, pkt, size);
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}
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static int voc_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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    return voc_get_packet(s, pkt, s->streams[0], 0);
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}
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AVInputFormat voc_demuxer = {
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    "voc",
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    "Creative Voice File format",
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    sizeof(voc_dec_context_t),
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    voc_probe,
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    voc_read_header,
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    voc_read_packet,
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    .codec_tag=(const AVCodecTag*[]){voc_codec_tags, 0},
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};