FFmpeg/libavformat/swfdec.c

/*
 * Flash Compatible Streaming Format
 * Copyright (c) 2000 Fabrice Bellard.
 * Copyright (c) 2003 Tinic Uro.
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "swf.h"

/*********************************************/
/* Extract FLV encoded frame and MP3 from swf
   Note that the detection of the real frame
   is inaccurate at this point as it can be
   quite tricky to determine, you almost certainly
   will get a bad audio/video sync */

static int get_swf_tag(ByteIOContext *pb, int *len_ptr)
{
    int tag, len;

    if (url_feof(pb))
        return -1;

    tag = get_le16(pb);
    len = tag & 0x3f;
    tag = tag >> 6;
    if (len == 0x3f) {
        len = get_le32(pb);
    }
//    av_log(NULL, AV_LOG_DEBUG, "Tag: %d - Len: %d\n", tag, len);
    *len_ptr = len;
    return tag;
}


static int swf_probe(AVProbeData *p)
{
    /* check file header */
    if ((p->buf[0] == 'F' || p->buf[0] == 'C') && p->buf[1] == 'W' &&
        p->buf[2] == 'S')
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int swf_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
    SWFContext *swf = s->priv_data;
    ByteIOContext *pb = s->pb;
    int nbits, len, tag;

    tag = get_be32(pb) & 0xffffff00;

    if (tag == MKBETAG('C', 'W', 'S', 0)) {
        av_log(s, AV_LOG_ERROR, "Compressed SWF format not supported\n");
        return AVERROR(EIO);
    }
    if (tag != MKBETAG('F', 'W', 'S', 0))
        return AVERROR(EIO);
    get_le32(pb);
    /* skip rectangle size */
    nbits = get_byte(pb) >> 3;
    len = (4 * nbits - 3 + 7) / 8;
    url_fskip(pb, len);
    swf->frame_rate = get_le16(pb); /* 8.8 fixed */
    get_le16(pb); /* frame count */

    swf->samples_per_frame = 0;
    s->ctx_flags |= AVFMTCTX_NOHEADER;
    return 0;
}

static int swf_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    SWFContext *swf = s->priv_data;
    ByteIOContext *pb = s->pb;
    AVStream *vst = NULL, *ast = NULL, *st = 0;
    int tag, len, i, frame, v;

    for(;;) {
        tag = get_swf_tag(pb, &len);
        if (tag < 0)
            return AVERROR(EIO);
        if (tag == TAG_VIDEOSTREAM && !vst) {
            int ch_id = get_le16(pb);
            get_le16(pb);
            get_le16(pb);
            get_le16(pb);
            get_byte(pb);
            /* Check for FLV1 */
            vst = av_new_stream(s, ch_id);
            if (!vst)
                return -1;
            vst->codec->codec_type = CODEC_TYPE_VIDEO;
            vst->codec->codec_id = codec_get_id(swf_codec_tags, get_byte(pb));
            av_set_pts_info(vst, 64, 256, swf->frame_rate);
            vst->codec->time_base = (AVRational){ 256, swf->frame_rate };
            len -= 10;
        } else if ((tag == TAG_STREAMHEAD || tag == TAG_STREAMHEAD2) && !ast) {
            /* streaming found */
            int sample_rate_code;
            get_byte(pb);
            v = get_byte(pb);
            swf->samples_per_frame = get_le16(pb);
            ast = av_new_stream(s, -1); /* -1 to avoid clash with video stream ch_id */
            if (!ast)
                return -1;
            swf->audio_stream_index = ast->index;
            ast->codec->channels = 1 + (v&1);
            ast->codec->codec_type = CODEC_TYPE_AUDIO;
            ast->codec->codec_id = codec_get_id(swf_audio_codec_tags, (v>>4) & 15);
            ast->need_parsing = AVSTREAM_PARSE_FULL;
            sample_rate_code= (v>>2) & 3;
            if (!sample_rate_code)
                return AVERROR(EIO);
            ast->codec->sample_rate = 11025 << (sample_rate_code-1);
            av_set_pts_info(ast, 64, 1, ast->codec->sample_rate);
            len -= 4;
        } else if (tag == TAG_VIDEOFRAME) {
            int ch_id = get_le16(pb);
            len -= 2;
            for(i=0; i<s->nb_streams; i++) {
                st = s->streams[i];
                if (st->codec->codec_type == CODEC_TYPE_VIDEO && st->id == ch_id) {
                    frame = get_le16(pb);
                    av_get_packet(pb, pkt, len-2);
                    pkt->pts = frame;
                    pkt->stream_index = st->index;
                    return pkt->size;
                }
            }
        } else if (tag == TAG_STREAMBLOCK) {
            st = s->streams[swf->audio_stream_index];
            if (st->codec->codec_id == CODEC_ID_MP3) {
                url_fskip(pb, 4);
                av_get_packet(pb, pkt, len-4);
            } else { // ADPCM, PCM
                av_get_packet(pb, pkt, len);
            }
            pkt->stream_index = st->index;
            return pkt->size;
        } else if (tag == TAG_JPEG2) {
            for (i=0; i<s->nb_streams; i++) {
                st = s->streams[i];
                if (st->id == -2)
                    break;
            }
            if (i == s->nb_streams) {
                vst = av_new_stream(s, -2); /* -2 to avoid clash with video stream and audio stream */
                if (!vst)
                    return -1;
                vst->codec->codec_type = CODEC_TYPE_VIDEO;
                vst->codec->codec_id = CODEC_ID_MJPEG;
                av_set_pts_info(vst, 64, 256, swf->frame_rate);
                vst->codec->time_base = (AVRational){ 256, swf->frame_rate };
                st = vst;
            }
            get_le16(pb); /* BITMAP_ID */
            av_new_packet(pkt, len-2);
            get_buffer(pb, pkt->data, 4);
            if (AV_RB32(pkt->data) == 0xffd8ffd9 ||
                AV_RB32(pkt->data) == 0xffd9ffd8) {
                /* old SWF files containing SOI/EOI as data start */
                /* files created by swink have reversed tag */
                pkt->size -= 4;
                get_buffer(pb, pkt->data, pkt->size);
            } else {
                get_buffer(pb, pkt->data + 4, pkt->size - 4);
            }
            pkt->stream_index = st->index;
            return pkt->size;
        }
        url_fskip(pb, len);
    }
    return 0;
}

static int swf_read_close(AVFormatContext *s)
{
    return 0;
}

AVInputFormat swf_demuxer = {
    "swf",
    "Flash format",
    sizeof(SWFContext),
    swf_probe,
    swf_read_header,
    swf_read_packet,
    swf_read_close,
};