PeerStreamer

/*

 * Sierra VMD Format Demuxer

 * Copyright (c) 2004 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 sierravmd.c

 * Sierra VMD file demuxer

 * by Vladimir "VAG" Gneushev (vagsoft at mail.ru)

 * for more information on the Sierra VMD file format, visit:

 *   http://www.pcisys.net/~melanson/codecs/

 */

#include "avformat.h"

#define VMD_HEADER_SIZE 0x0330

#define BYTES_PER_FRAME_RECORD 16

typedef struct {

  int stream_index;

  offset_t frame_offset;

  unsigned int frame_size;

  int64_t pts;

  int keyframe;

  unsigned char frame_record[BYTES_PER_FRAME_RECORD];

} vmd_frame_t;

typedef struct VmdDemuxContext {

    int video_stream_index;

    int audio_stream_index;

    unsigned int audio_type;

    unsigned int audio_samplerate;

    unsigned int audio_bits;

    unsigned int audio_channels;

    unsigned int frame_count;

    vmd_frame_t *frame_table;

    unsigned int current_frame;

    int sample_rate;

    int64_t audio_sample_counter;

    int audio_frame_divisor;

    int audio_block_align;

    unsigned char vmd_header[VMD_HEADER_SIZE];

} VmdDemuxContext;

static int vmd_probe(AVProbeData *p)

{

    if (p->buf_size < 2)

        return 0;

    /* check if the first 2 bytes of the file contain the appropriate size

     * of a VMD header chunk */

    if (LE_16(&p->buf[0]) != VMD_HEADER_SIZE - 2)

        return 0;

    /* only return half certainty since this check is a bit sketchy */

    return AVPROBE_SCORE_MAX / 2;

}

/* This is a support function to determine the duration, in sample

 * frames, of a particular audio chunk, taking into account silent

 * encodings. */

static int vmd_calculate_audio_duration(unsigned char *audio_chunk,

    int audio_chunk_size, int block_align)

{

    unsigned char *p = audio_chunk + 16;

    unsigned char *p_end = audio_chunk + audio_chunk_size;

    int total_samples = 0;

    unsigned int sound_flags;

    if (audio_chunk_size < 16)

        return 0;

    sound_flags = LE_32(p);

    p += 4;

    while (p < p_end) {

        total_samples += block_align;

        if ((sound_flags & 0x01) == 0)

            p += block_align;

        sound_flags >>= 1;

    }

    return total_samples;

}

static int vmd_read_header(AVFormatContext *s,

                           AVFormatParameters *ap)

{

    VmdDemuxContext *vmd = (VmdDemuxContext *)s->priv_data;

    ByteIOContext *pb = &s->pb;

    AVStream *st;

    unsigned int toc_offset;

    unsigned char *raw_frame_table;

    int raw_frame_table_size;

    unsigned char *current_frame_record;

    offset_t current_offset;

    int i;

    unsigned int total_frames;

    int64_t video_pts_inc;

    int64_t current_video_pts = 0;

    /* fetch the main header, including the 2 header length bytes */

    url_fseek(pb, 0, SEEK_SET);

    if (get_buffer(pb, vmd->vmd_header, VMD_HEADER_SIZE) != VMD_HEADER_SIZE)

        return AVERROR_IO;

    vmd->audio_sample_counter = 0;

    vmd->audio_frame_divisor = 1;

    vmd->audio_block_align = 1;

    /* start up the decoders */

    st = av_new_stream(s, 0);

    if (!st)

        return AVERROR_NOMEM;

    av_set_pts_info(st, 33, 1, 90000);

    vmd->video_stream_index = st->index;

    st->codec->codec_type = CODEC_TYPE_VIDEO;

    st->codec->codec_id = CODEC_ID_VMDVIDEO;

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

    st->codec->width = LE_16(&vmd->vmd_header[12]);

    st->codec->height = LE_16(&vmd->vmd_header[14]);

    st->codec->extradata_size = VMD_HEADER_SIZE;

    st->codec->extradata = av_mallocz(VMD_HEADER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);

    memcpy(st->codec->extradata, vmd->vmd_header, VMD_HEADER_SIZE);

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

    vmd->sample_rate = LE_16(&vmd->vmd_header[804]);

    if (vmd->sample_rate) {

        st = av_new_stream(s, 0);

        if (!st)

            return AVERROR_NOMEM;

        av_set_pts_info(st, 33, 1, 90000);

        vmd->audio_stream_index = st->index;

        st->codec->codec_type = CODEC_TYPE_AUDIO;

        st->codec->codec_id = CODEC_ID_VMDAUDIO;

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

        st->codec->channels = (vmd->vmd_header[811] & 0x80) ? 2 : 1;

        st->codec->sample_rate = vmd->sample_rate;

        st->codec->block_align = vmd->audio_block_align =

            LE_16(&vmd->vmd_header[806]);

        if (st->codec->block_align & 0x8000) {

            st->codec->bits_per_sample = 16;

            st->codec->block_align = -(st->codec->block_align - 0x10000);

        } else

            st->codec->bits_per_sample = 16;

//            st->codec->bits_per_sample = 8;

        st->codec->bit_rate = st->codec->sample_rate *

            st->codec->bits_per_sample * st->codec->channels;

        /* for calculating pts */

        vmd->audio_frame_divisor = st->codec->bits_per_sample / 8 /

            st->codec->channels;

        video_pts_inc = 90000;

        video_pts_inc *= st->codec->block_align;

        video_pts_inc /= st->codec->sample_rate;

    } else {

        /* if no audio, assume 10 frames/second */

        video_pts_inc = 90000 / 10;

    }

    /* skip over the offset table and load the table of contents; don't

     * care about the offset table since demuxer will calculate those

     * independently */

    toc_offset = LE_32(&vmd->vmd_header[812]);

    vmd->frame_count = LE_16(&vmd->vmd_header[6]);

    url_fseek(pb, toc_offset + vmd->frame_count * 6, SEEK_SET);

    /* each on-disk VMD frame has an audio part and a video part; demuxer

     * accounts them separately */

    if(vmd->sample_rate)

        vmd->frame_count *= 2;

    raw_frame_table = NULL;

    vmd->frame_table = NULL;

    raw_frame_table_size = vmd->frame_count * BYTES_PER_FRAME_RECORD;

    raw_frame_table = av_malloc(raw_frame_table_size);

    vmd->frame_table = av_malloc(vmd->frame_count * sizeof(vmd_frame_t));

    if (!raw_frame_table || !vmd->frame_table) {

        av_free(raw_frame_table);

        av_free(vmd->frame_table);

        return AVERROR_NOMEM;

    }

    if (get_buffer(pb, raw_frame_table, raw_frame_table_size) !=

        raw_frame_table_size) {

        av_free(raw_frame_table);

        av_free(vmd->frame_table);

        return AVERROR_IO;

    }

    current_offset = LE_32(&vmd->vmd_header[20]);

    current_frame_record = raw_frame_table;

    total_frames = vmd->frame_count;

    i = 0;

    while (total_frames--) {

        /* if the frame size is 0, do not count the frame and bring the

         * total frame count down */

        // note, we limit the size to 1Gb to ensure that we dont end up overflowing the size integer used to allocate the memory

        vmd->frame_table[i].frame_size = LE_32(&current_frame_record[2]) & 0x3FFFFFFF;

        /* this logic is present so that 0-length audio chunks are not

         * accounted */

        if (!vmd->frame_table[i].frame_size) {

            vmd->frame_count--;  /* one less frame to count */

            current_frame_record += BYTES_PER_FRAME_RECORD;

            continue;

        }

        if (current_frame_record[0] == 0x02)

            vmd->frame_table[i].stream_index = vmd->video_stream_index;

        else

            vmd->frame_table[i].stream_index = vmd->audio_stream_index;

        vmd->frame_table[i].frame_offset = current_offset;

        current_offset += vmd->frame_table[i].frame_size;

        memcpy(vmd->frame_table[i].frame_record, current_frame_record,

            BYTES_PER_FRAME_RECORD);

        /* figure out the pts for this frame */

        if (current_frame_record[0] == 0x02) {

            vmd->frame_table[i].pts = current_video_pts;

            current_video_pts += video_pts_inc;

        } else if (current_frame_record[0] == 0x01) {

            /* figure out the pts during the dispatch phase */

            vmd->frame_table[i].pts = 0;

        }

        current_frame_record += BYTES_PER_FRAME_RECORD;

        i++;

    }

    av_free(raw_frame_table);

    vmd->current_frame = 0;

    return 0;

}

static int vmd_read_packet(AVFormatContext *s,

                           AVPacket *pkt)

{

    VmdDemuxContext *vmd = (VmdDemuxContext *)s->priv_data;

    ByteIOContext *pb = &s->pb;

    int ret = 0;

    vmd_frame_t *frame;

    if (vmd->current_frame >= vmd->frame_count)

        return AVERROR_IO;

    frame = &vmd->frame_table[vmd->current_frame];

    /* position the stream (will probably be there already) */

    url_fseek(pb, frame->frame_offset, SEEK_SET);

    if (av_new_packet(pkt, frame->frame_size + BYTES_PER_FRAME_RECORD))

        return AVERROR_NOMEM;

    pkt->pos= url_ftell(pb);

    memcpy(pkt->data, frame->frame_record, BYTES_PER_FRAME_RECORD);

    ret = get_buffer(pb, pkt->data + BYTES_PER_FRAME_RECORD,

        frame->frame_size);

    if (ret != frame->frame_size) {

        av_free_packet(pkt);

        ret = AVERROR_IO;

    }

    pkt->stream_index = frame->stream_index;

    if (frame->frame_record[0] == 0x02)

        pkt->pts = frame->pts;

    else {

        pkt->pts = vmd->audio_sample_counter;

        pkt->pts *= 90000;

        pkt->pts /= vmd->sample_rate;

//        pkt->pts /= vmd->audio_frame_divisor;

        vmd->audio_sample_counter += vmd_calculate_audio_duration(

            pkt->data, pkt->size, vmd->audio_block_align);

    }

av_log(NULL, AV_LOG_INFO, " dispatching %s frame with %d bytes and pts %"PRId64" (%0.1f sec)\n",

  (frame->frame_record[0] == 0x02) ? "video" : "audio",

  frame->frame_size + BYTES_PER_FRAME_RECORD,

  pkt->pts, (float)(pkt->pts / 90000.0));

    vmd->current_frame++;

    return ret;

}

static int vmd_read_close(AVFormatContext *s)

{

    VmdDemuxContext *vmd = (VmdDemuxContext *)s->priv_data;

    av_free(vmd->frame_table);

    return 0;

}

static AVInputFormat vmd_iformat = {

    "vmd",

    "Sierra VMD format",

    sizeof(VmdDemuxContext),

    vmd_probe,

    vmd_read_header,

    vmd_read_packet,

    vmd_read_close,

};

int vmd_init(void)

{

    av_register_input_format(&vmd_iformat);

    return 0;

}