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/*
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 * Id Quake II CIN File Demuxer
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 * Copyright (c) 2003 The ffmpeg Project
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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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/**
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 * @file idcin.c
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 * Id Quake II CIN file demuxer by Mike Melanson (melanson@pcisys.net)
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 * For more information about the Id CIN format, visit:
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 *   http://www.csse.monash.edu.au/~timf/
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 *
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 * CIN is a somewhat quirky and ill-defined format. Here are some notes
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 * for anyone trying to understand the technical details of this format:
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 *
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 * The format has no definite file signature. This is problematic for a
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 * general-purpose media player that wants to automatically detect file
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 * types. However, a CIN file does start with 5 32-bit numbers that
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 * specify audio and video parameters. This demuxer gets around the lack
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 * of file signature by performing sanity checks on those parameters.
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 * Probabalistically, this is a reasonable solution since the number of
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 * valid combinations of the 5 parameters is a very small subset of the
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 * total 160-bit number space.
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 *
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 * Refer to the function idcin_probe() for the precise A/V parameters
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 * that this demuxer allows.
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 *
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 * Next, each audio and video frame has a duration of 1/14 sec. If the
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 * audio sample rate is a multiple of the common frequency 22050 Hz it will
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 * divide evenly by 14. However, if the sample rate is 11025 Hz:
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 *   11025 (samples/sec) / 14 (frames/sec) = 787.5 (samples/frame)
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 * The way the CIN stores audio in this case is by storing 787 sample
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 * frames in the first audio frame and 788 sample frames in the second
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 * audio frame. Therefore, the total number of bytes in an audio frame
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 * is given as:
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 *   audio frame #0: 787 * (bytes/sample) * (# channels) bytes in frame
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 *   audio frame #1: 788 * (bytes/sample) * (# channels) bytes in frame
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 *   audio frame #2: 787 * (bytes/sample) * (# channels) bytes in frame
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 *   audio frame #3: 788 * (bytes/sample) * (# channels) bytes in frame
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 *
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 * Finally, not all Id CIN creation tools agree on the resolution of the
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 * color palette, apparently. Some creation tools specify red, green, and
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 * blue palette components in terms of 6-bit VGA color DAC values which
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 * range from 0..63. Other tools specify the RGB components as full 8-bit
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 * values that range from 0..255. Since there are no markers in the file to
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 * differentiate between the two variants, this demuxer uses the following
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 * heuristic:
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 *   - load the 768 palette bytes from disk
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 *   - assume that they will need to be shifted left by 2 bits to
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 *     transform them from 6-bit values to 8-bit values
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 *   - scan through all 768 palette bytes
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 *     - if any bytes exceed 63, do not shift the bytes at all before
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 *       transmitting them to the video decoder
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 */
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#include "avformat.h"
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#define HUFFMAN_TABLE_SIZE (64 * 1024)
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#define FRAME_PTS_INC (90000 / 14)
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typedef struct IdcinDemuxContext {
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    int video_stream_index;
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    int audio_stream_index;
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    int audio_chunk_size1;
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    int audio_chunk_size2;
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    /* demux state variables */
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    int current_audio_chunk;
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    int next_chunk_is_video;
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    int audio_present;
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    int64_t pts;
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    AVPaletteControl palctrl;
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} IdcinDemuxContext;
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static int idcin_probe(AVProbeData *p)
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{
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    unsigned int number;
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    /*
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     * This is what you could call a "probabilistic" file check: Id CIN
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     * files don't have a definite file signature. In lieu of such a marker,
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     * perform sanity checks on the 5 32-bit header fields:
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     *  width, height: greater than 0, less than or equal to 1024
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     * audio sample rate: greater than or equal to 8000, less than or
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     *  equal to 48000, or 0 for no audio
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     * audio sample width (bytes/sample): 0 for no audio, or 1 or 2
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     * audio channels: 0 for no audio, or 1 or 2
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     */
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    /* cannot proceed without 20 bytes */
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    if (p->buf_size < 20)
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        return 0;
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    /* check the video width */
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    number = AV_RL32(&p->buf[0]);
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    if ((number == 0) || (number > 1024))
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       return 0;
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    /* check the video height */
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    number = AV_RL32(&p->buf[4]);
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    if ((number == 0) || (number > 1024))
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       return 0;
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    /* check the audio sample rate */
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    number = AV_RL32(&p->buf[8]);
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    if ((number != 0) && ((number < 8000) | (number > 48000)))
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        return 0;
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    /* check the audio bytes/sample */
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    number = AV_RL32(&p->buf[12]);
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    if (number > 2)
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        return 0;
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    /* check the audio channels */
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    number = AV_RL32(&p->buf[16]);
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    if (number > 2)
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        return 0;
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    /* return half certainly since this check is a bit sketchy */
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    return AVPROBE_SCORE_MAX / 2;
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}
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static int idcin_read_header(AVFormatContext *s,
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                             AVFormatParameters *ap)
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{
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    ByteIOContext *pb = &s->pb;
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    IdcinDemuxContext *idcin = (IdcinDemuxContext *)s->priv_data;
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    AVStream *st;
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    unsigned int width, height;
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    unsigned int sample_rate, bytes_per_sample, channels;
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    /* get the 5 header parameters */
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    width = get_le32(pb);
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    height = get_le32(pb);
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    sample_rate = get_le32(pb);
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    bytes_per_sample = get_le32(pb);
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    channels = get_le32(pb);
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    st = av_new_stream(s, 0);
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    if (!st)
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        return AVERROR_NOMEM;
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    av_set_pts_info(st, 33, 1, 90000);
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    idcin->video_stream_index = st->index;
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    st->codec->codec_type = CODEC_TYPE_VIDEO;
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    st->codec->codec_id = CODEC_ID_IDCIN;
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    st->codec->codec_tag = 0;  /* no fourcc */
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    st->codec->width = width;
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    st->codec->height = height;
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    /* load up the Huffman tables into extradata */
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    st->codec->extradata_size = HUFFMAN_TABLE_SIZE;
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    st->codec->extradata = av_malloc(HUFFMAN_TABLE_SIZE);
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    if (get_buffer(pb, st->codec->extradata, HUFFMAN_TABLE_SIZE) !=
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        HUFFMAN_TABLE_SIZE)
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        return AVERROR_IO;
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    /* save a reference in order to transport the palette */
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    st->codec->palctrl = &idcin->palctrl;
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    /* if sample rate is 0, assume no audio */
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    if (sample_rate) {
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        idcin->audio_present = 1;
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        st = av_new_stream(s, 0);
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        if (!st)
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            return AVERROR_NOMEM;
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        av_set_pts_info(st, 33, 1, 90000);
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        idcin->audio_stream_index = st->index;
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        st->codec->codec_type = CODEC_TYPE_AUDIO;
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        st->codec->codec_tag = 1;
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        st->codec->channels = channels;
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        st->codec->sample_rate = sample_rate;
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        st->codec->bits_per_sample = bytes_per_sample * 8;
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        st->codec->bit_rate = sample_rate * bytes_per_sample * 8 * channels;
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        st->codec->block_align = bytes_per_sample * channels;
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        if (bytes_per_sample == 1)
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            st->codec->codec_id = CODEC_ID_PCM_U8;
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        else
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            st->codec->codec_id = CODEC_ID_PCM_S16LE;
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        if (sample_rate % 14 != 0) {
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            idcin->audio_chunk_size1 = (sample_rate / 14) *
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            bytes_per_sample * channels;
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            idcin->audio_chunk_size2 = (sample_rate / 14 + 1) *
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                bytes_per_sample * channels;
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        } else {
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            idcin->audio_chunk_size1 = idcin->audio_chunk_size2 =
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                (sample_rate / 14) * bytes_per_sample * channels;
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        }
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        idcin->current_audio_chunk = 0;
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    } else
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        idcin->audio_present = 1;
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    idcin->next_chunk_is_video = 1;
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    idcin->pts = 0;
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    return 0;
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}
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static int idcin_read_packet(AVFormatContext *s,
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                             AVPacket *pkt)
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{
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    int ret;
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    unsigned int command;
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    unsigned int chunk_size;
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    IdcinDemuxContext *idcin = (IdcinDemuxContext *)s->priv_data;
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    ByteIOContext *pb = &s->pb;
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    int i;
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    int palette_scale;
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    unsigned char r, g, b;
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    unsigned char palette_buffer[768];
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    if (url_feof(&s->pb))
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        return AVERROR_IO;
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    if (idcin->next_chunk_is_video) {
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        command = get_le32(pb);
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        if (command == 2) {
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            return AVERROR_IO;
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        } else if (command == 1) {
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            /* trigger a palette change */
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            idcin->palctrl.palette_changed = 1;
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            if (get_buffer(pb, palette_buffer, 768) != 768)
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                return AVERROR_IO;
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            /* scale the palette as necessary */
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            palette_scale = 2;
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            for (i = 0; i < 768; i++)
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                if (palette_buffer[i] > 63) {
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                    palette_scale = 0;
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                    break;
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                }
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            for (i = 0; i < 256; i++) {
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                r = palette_buffer[i * 3    ] << palette_scale;
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                g = palette_buffer[i * 3 + 1] << palette_scale;
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                b = palette_buffer[i * 3 + 2] << palette_scale;
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                idcin->palctrl.palette[i] = (r << 16) | (g << 8) | (b);
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            }
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        }
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        chunk_size = get_le32(pb);
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        /* skip the number of decoded bytes (always equal to width * height) */
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        url_fseek(pb, 4, SEEK_CUR);
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        chunk_size -= 4;
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        ret= av_get_packet(pb, pkt, chunk_size);
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        if (ret != chunk_size)
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            return AVERROR_IO;
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        pkt->stream_index = idcin->video_stream_index;
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        pkt->pts = idcin->pts;
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    } else {
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        /* send out the audio chunk */
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        if (idcin->current_audio_chunk)
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            chunk_size = idcin->audio_chunk_size2;
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        else
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            chunk_size = idcin->audio_chunk_size1;
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        ret= av_get_packet(pb, pkt, chunk_size);
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        if (ret != chunk_size)
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            return AVERROR_IO;
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        pkt->stream_index = idcin->audio_stream_index;
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        pkt->pts = idcin->pts;
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        idcin->current_audio_chunk ^= 1;
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        idcin->pts += FRAME_PTS_INC;
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    }
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    if (idcin->audio_present)
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        idcin->next_chunk_is_video ^= 1;
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    return ret;
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}
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static int idcin_read_close(AVFormatContext *s)
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{
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    return 0;
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}
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AVInputFormat idcin_demuxer = {
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    "idcin",
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    "Id CIN format",
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    sizeof(IdcinDemuxContext),
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    idcin_probe,
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    idcin_read_header,
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    idcin_read_packet,
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    idcin_read_close,
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};