PeerStreamer

/*

 * Id Quake II CIN File Demuxer

 * Copyright (c) 2003 The ffmpeg Project

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file idcin.c

 * Id Quake II CIN file demuxer by Mike Melanson (melanson@pcisys.net)

 * For more information about the Id CIN format, visit:

 *   http://www.csse.monash.edu.au/~timf/

 *

 * CIN is a somewhat quirky and ill-defined format. Here are some notes

 * for anyone trying to understand the technical details of this format:

 *

 * The format has no definite file signature. This is problematic for a

 * general-purpose media player that wants to automatically detect file

 * types. However, a CIN file does start with 5 32-bit numbers that

 * specify audio and video parameters. This demuxer gets around the lack

 * of file signature by performing sanity checks on those parameters.

 * Probabalistically, this is a reasonable solution since the number of

 * valid combinations of the 5 parameters is a very small subset of the

 * total 160-bit number space.

 *

 * Refer to the function idcin_probe() for the precise A/V parameters

 * that this demuxer allows.

 *

 * Next, each audio and video frame has a duration of 1/14 sec. If the

 * audio sample rate is a multiple of the common frequency 22050 Hz it will

 * divide evenly by 14. However, if the sample rate is 11025 Hz:

 *   11025 (samples/sec) / 14 (frames/sec) = 787.5 (samples/frame)

 * The way the CIN stores audio in this case is by storing 787 sample

 * frames in the first audio frame and 788 sample frames in the second

 * audio frame. Therefore, the total number of bytes in an audio frame

 * is given as:

 *   audio frame #0: 787 * (bytes/sample) * (# channels) bytes in frame

 *   audio frame #1: 788 * (bytes/sample) * (# channels) bytes in frame

 *   audio frame #2: 787 * (bytes/sample) * (# channels) bytes in frame

 *   audio frame #3: 788 * (bytes/sample) * (# channels) bytes in frame

 *

 * Finally, not all Id CIN creation tools agree on the resolution of the

 * color palette, apparently. Some creation tools specify red, green, and

 * blue palette components in terms of 6-bit VGA color DAC values which

 * range from 0..63. Other tools specify the RGB components as full 8-bit

 * values that range from 0..255. Since there are no markers in the file to

 * differentiate between the two variants, this demuxer uses the following

 * heuristic:

 *   - load the 768 palette bytes from disk

 *   - assume that they will need to be shifted left by 2 bits to

 *     transform them from 6-bit values to 8-bit values

 *   - scan through all 768 palette bytes

 *     - if any bytes exceed 63, do not shift the bytes at all before

 *       transmitting them to the video decoder

 */

#include "avformat.h"

#define HUFFMAN_TABLE_SIZE (64 * 1024)

#define FRAME_PTS_INC (90000 / 14)

typedef struct IdcinDemuxContext {

    int video_stream_index;

    int audio_stream_index;

    int audio_chunk_size1;

    int audio_chunk_size2;

    /* demux state variables */

    int current_audio_chunk;

    int next_chunk_is_video;

    int audio_present;

    int64_t pts;

    AVPaletteControl palctrl;

} IdcinDemuxContext;

static int idcin_probe(AVProbeData *p)

{

    unsigned int number;

    /*

     * This is what you could call a "probabilistic" file check: Id CIN

     * files don't have a definite file signature. In lieu of such a marker,

     * perform sanity checks on the 5 32-bit header fields:

     *  width, height: greater than 0, less than or equal to 1024

     * audio sample rate: greater than or equal to 8000, less than or

     *  equal to 48000, or 0 for no audio

     * audio sample width (bytes/sample): 0 for no audio, or 1 or 2

     * audio channels: 0 for no audio, or 1 or 2

     */

    /* cannot proceed without 20 bytes */

    if (p->buf_size < 20)

        return 0;

    /* check the video width */

    number = LE_32(&p->buf[0]);

    if ((number == 0) || (number > 1024))

       return 0;

    /* check the video height */

    number = LE_32(&p->buf[4]);

    if ((number == 0) || (number > 1024))

       return 0;

    /* check the audio sample rate */

    number = LE_32(&p->buf[8]);

    if ((number != 0) && ((number < 8000) | (number > 48000)))

        return 0;

    /* check the audio bytes/sample */

    number = LE_32(&p->buf[12]);

    if (number > 2)

        return 0;

    /* check the audio channels */

    number = LE_32(&p->buf[16]);

    if (number > 2)

        return 0;

    /* return half certainly since this check is a bit sketchy */

    return AVPROBE_SCORE_MAX / 2;

}

static int idcin_read_header(AVFormatContext *s,

                             AVFormatParameters *ap)

{

    ByteIOContext *pb = &s->pb;

    IdcinDemuxContext *idcin = (IdcinDemuxContext *)s->priv_data;

    AVStream *st;

    unsigned int width, height;

    unsigned int sample_rate, bytes_per_sample, channels;

    /* get the 5 header parameters */

    width = get_le32(pb);

    height = get_le32(pb);

    sample_rate = get_le32(pb);

    bytes_per_sample = get_le32(pb);

    channels = get_le32(pb);

    st = av_new_stream(s, 0);

    if (!st)

        return AVERROR_NOMEM;

    av_set_pts_info(st, 33, 1, 90000);

    idcin->video_stream_index = st->index;

    st->codec->codec_type = CODEC_TYPE_VIDEO;

    st->codec->codec_id = CODEC_ID_IDCIN;

    st->codec->codec_tag = 0;  /* no fourcc */

    st->codec->width = width;

    st->codec->height = height;

    /* load up the Huffman tables into extradata */

    st->codec->extradata_size = HUFFMAN_TABLE_SIZE;

    st->codec->extradata = av_malloc(HUFFMAN_TABLE_SIZE);

    if (get_buffer(pb, st->codec->extradata, HUFFMAN_TABLE_SIZE) !=

        HUFFMAN_TABLE_SIZE)

        return AVERROR_IO;

    /* save a reference in order to transport the palette */

    st->codec->palctrl = &idcin->palctrl;

    /* if sample rate is 0, assume no audio */

    if (sample_rate) {

        idcin->audio_present = 1;

        st = av_new_stream(s, 0);

        if (!st)

            return AVERROR_NOMEM;

        av_set_pts_info(st, 33, 1, 90000);

        idcin->audio_stream_index = st->index;

        st->codec->codec_type = CODEC_TYPE_AUDIO;

        st->codec->codec_tag = 1;

        st->codec->channels = channels;

        st->codec->sample_rate = sample_rate;

        st->codec->bits_per_sample = bytes_per_sample * 8;

        st->codec->bit_rate = sample_rate * bytes_per_sample * 8 * channels;

        st->codec->block_align = bytes_per_sample * channels;

        if (bytes_per_sample == 1)

            st->codec->codec_id = CODEC_ID_PCM_U8;

        else

            st->codec->codec_id = CODEC_ID_PCM_S16LE;

        if (sample_rate % 14 != 0) {

            idcin->audio_chunk_size1 = (sample_rate / 14) *

            bytes_per_sample * channels;

            idcin->audio_chunk_size2 = (sample_rate / 14 + 1) *

                bytes_per_sample * channels;

        } else {

            idcin->audio_chunk_size1 = idcin->audio_chunk_size2 =

                (sample_rate / 14) * bytes_per_sample * channels;

        }

        idcin->current_audio_chunk = 0;

    } else

        idcin->audio_present = 1;

    idcin->next_chunk_is_video = 1;

    idcin->pts = 0;

    return 0;

}

static int idcin_read_packet(AVFormatContext *s,

                             AVPacket *pkt)

{

    int ret;

    unsigned int command;

    unsigned int chunk_size;

    IdcinDemuxContext *idcin = (IdcinDemuxContext *)s->priv_data;

    ByteIOContext *pb = &s->pb;

    int i;

    int palette_scale;

    unsigned char r, g, b;

    unsigned char palette_buffer[768];

    if (url_feof(&s->pb))

        return AVERROR_IO;

    if (idcin->next_chunk_is_video) {

        command = get_le32(pb);

        if (command == 2) {

            return AVERROR_IO;

        } else if (command == 1) {

            /* trigger a palette change */

            idcin->palctrl.palette_changed = 1;

            if (get_buffer(pb, palette_buffer, 768) != 768)

                return AVERROR_IO;

            /* scale the palette as necessary */

            palette_scale = 2;

            for (i = 0; i < 768; i++)

                if (palette_buffer[i] > 63) {

                    palette_scale = 0;

                    break;

                }

            for (i = 0; i < 256; i++) {

                r = palette_buffer[i * 3    ] << palette_scale;

                g = palette_buffer[i * 3 + 1] << palette_scale;

                b = palette_buffer[i * 3 + 2] << palette_scale;

                idcin->palctrl.palette[i] = (r << 16) | (g << 8) | (b);

            }

        }

        chunk_size = get_le32(pb);

        /* skip the number of decoded bytes (always equal to width * height) */

        url_fseek(pb, 4, SEEK_CUR);

        chunk_size -= 4;

        ret= av_get_packet(pb, pkt, chunk_size);

        if (ret != chunk_size)

            return AVERROR_IO;

        pkt->stream_index = idcin->video_stream_index;

        pkt->pts = idcin->pts;

    } else {

        /* send out the audio chunk */

        if (idcin->current_audio_chunk)

            chunk_size = idcin->audio_chunk_size2;

        else

            chunk_size = idcin->audio_chunk_size1;

        ret= av_get_packet(pb, pkt, chunk_size);

        if (ret != chunk_size)

            return AVERROR_IO;

        pkt->stream_index = idcin->audio_stream_index;

        pkt->pts = idcin->pts;

        idcin->current_audio_chunk ^= 1;

        idcin->pts += FRAME_PTS_INC;

    }

    if (idcin->audio_present)

        idcin->next_chunk_is_video ^= 1;

    return ret;

}

static int idcin_read_close(AVFormatContext *s)

{

    return 0;

}

static AVInputFormat idcin_iformat = {

    "idcin",

    "Id CIN format",

    sizeof(IdcinDemuxContext),

    idcin_probe,

    idcin_read_header,

    idcin_read_packet,

    idcin_read_close,

};

int idcin_init(void)

{

    av_register_input_format(&idcin_iformat);

    return 0;

}