PeerStreamer

/**

 * @file

 * Psygnosis YOP demuxer

 *

 * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>

 * derived from the code by

 * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>

 *

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; if not, write to the Free Software

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

 */

#include "libavutil/intreadwrite.h"

#include "avformat.h"

typedef struct yop_dec_context {

    AVPacket video_packet;

    int odd_frame;

    int frame_size;

    int audio_block_length;

    int palette_size;

} YopDecContext;

static int yop_probe(AVProbeData *probe_packet)

{

    if (AV_RB16(probe_packet->buf) == AV_RB16("YO")  &&

        probe_packet->buf[6]                         &&

        probe_packet->buf[7]                         &&

        !(probe_packet->buf[8] & 1)                  &&

        !(probe_packet->buf[10] & 1))

        return AVPROBE_SCORE_MAX * 3 / 4;

    return 0;

}

static int yop_read_header(AVFormatContext *s, AVFormatParameters *ap)

{

    YopDecContext *yop = s->priv_data;

    AVIOContext *pb  = s->pb;

    AVCodecContext *audio_dec, *video_dec;

    AVStream *audio_stream, *video_stream;

    int frame_rate, ret;

    audio_stream = av_new_stream(s, 0);

    video_stream = av_new_stream(s, 1);

    // Extra data that will be passed to the decoder

    video_stream->codec->extradata_size = 8;

    video_stream->codec->extradata = av_mallocz(video_stream->codec->extradata_size +

                                                FF_INPUT_BUFFER_PADDING_SIZE);

    if (!video_stream->codec->extradata)

        return AVERROR(ENOMEM);

    // Audio

    audio_dec               = audio_stream->codec;

    audio_dec->codec_type   = AVMEDIA_TYPE_AUDIO;

    audio_dec->codec_id     = CODEC_ID_ADPCM_IMA_WS;

    audio_dec->channels     = 1;

    audio_dec->sample_rate  = 22050;

    // Video

    video_dec               = video_stream->codec;

    video_dec->codec_type   = AVMEDIA_TYPE_VIDEO;

    video_dec->codec_id     = CODEC_ID_YOP;

    avio_skip(pb, 6);

    frame_rate              = avio_r8(pb);

    yop->frame_size         = avio_r8(pb) * 2048;

    video_dec->width        = avio_rl16(pb);

    video_dec->height       = avio_rl16(pb);

    video_stream->sample_aspect_ratio = (AVRational){1, 2};

    ret = avio_read(pb, video_dec->extradata, 8);

    if (ret < 8)

        return ret < 0 ? ret : AVERROR_EOF;

    yop->palette_size       = video_dec->extradata[0] * 3 + 4;

    yop->audio_block_length = AV_RL16(video_dec->extradata + 6);

    // 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920

    if (yop->audio_block_length < 920 ||

        yop->audio_block_length + yop->palette_size >= yop->frame_size) {

        av_log(s, AV_LOG_ERROR, "YOP has invalid header\n");

        return AVERROR_INVALIDDATA;

    }

    avio_seek(pb, 2048, SEEK_SET);

    av_set_pts_info(video_stream, 32, 1, frame_rate);

    return 0;

}

static int yop_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    YopDecContext *yop = s->priv_data;

    AVIOContext *pb  = s->pb;

    int ret;

    int actual_video_data_size = yop->frame_size -

                                 yop->audio_block_length - yop->palette_size;

    yop->video_packet.stream_index = 1;

    if (yop->video_packet.data) {

        *pkt                   =  yop->video_packet;

        yop->video_packet.data =  NULL;

        yop->video_packet.size =  0;

        pkt->data[0]           =  yop->odd_frame;

        pkt->flags             |= AV_PKT_FLAG_KEY;

        yop->odd_frame         ^= 1;

        return pkt->size;

    }

    ret = av_new_packet(&yop->video_packet,

                        yop->frame_size - yop->audio_block_length);

    if (ret < 0)

        return ret;

    yop->video_packet.pos = avio_tell(pb);

    ret = avio_read(pb, yop->video_packet.data, yop->palette_size);

    if (ret < 0) {

        goto err_out;

    }else if (ret < yop->palette_size) {

        ret = AVERROR_EOF;

        goto err_out;

    }

    ret = av_get_packet(pb, pkt, 920);

    if (ret < 0)

        goto err_out;

    // Set position to the start of the frame

    pkt->pos = yop->video_packet.pos;

    avio_skip(pb, yop->audio_block_length - ret);

    ret = avio_read(pb, yop->video_packet.data + yop->palette_size,

                     actual_video_data_size);

    if (ret < 0)

        goto err_out;

    else if (ret < actual_video_data_size)

        av_shrink_packet(&yop->video_packet, yop->palette_size + ret);

    // Arbitrarily return the audio data first

    return yop->audio_block_length;

err_out:

    av_free_packet(&yop->video_packet);

    return ret;

}

static int yop_read_close(AVFormatContext *s)

{

    YopDecContext *yop = s->priv_data;

    av_free_packet(&yop->video_packet);

    return 0;

}

static int yop_read_seek(AVFormatContext *s, int stream_index,

                         int64_t timestamp, int flags)

{

    YopDecContext *yop = s->priv_data;

    int64_t frame_pos, pos_min, pos_max;

    int frame_count;

    av_free_packet(&yop->video_packet);

    if (!stream_index)

        return -1;

    pos_min        = s->data_offset;

    pos_max        = avio_size(s->pb) - yop->frame_size;

    frame_count    = (pos_max - pos_min) / yop->frame_size;

    timestamp      = FFMAX(0, FFMIN(frame_count, timestamp));

    frame_pos      = timestamp * yop->frame_size + pos_min;

    yop->odd_frame = timestamp & 1;

    avio_seek(s->pb, frame_pos, SEEK_SET);

    return 0;

}

AVInputFormat ff_yop_demuxer = {

    "yop",

    NULL_IF_CONFIG_SMALL("Psygnosis YOP Format"),

    sizeof(YopDecContext),

    yop_probe,

    yop_read_header,

    yop_read_packet,

    yop_read_close,

    yop_read_seek,

    .extensions = "yop",

    .flags = AVFMT_GENERIC_INDEX,

};