smacker.c

ffmpeg源码分析

/*
 * Smacker decoder
 * Copyright (c) 2006 Konstantin Shishkov.
 *
 * 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
 */

/*
 * Based on http://wiki.multimedia.cx/index.php?title=Smacker
 */

#include "avformat.h"
#include "avi.h"
#include "bswap.h"

#define SMACKER_PAL 0x01

enum SAudFlags {
    SMK_AUD_PACKED  = 0x80000000,
    SMK_AUD_16BITS  = 0x20000000,
    SMK_AUD_STEREO  = 0x10000000,
    SMK_AUD_BINKAUD = 0x08000000,
    SMK_AUD_USEDCT  = 0x04000000
};

typedef struct SmackerContext {
    /* Smacker file header */
    uint32_t magic;
    uint32_t width, height;
    uint32_t frames;
    int      pts_inc;
    uint32_t flags;
    uint32_t audio[7];
    uint32_t treesize;
    uint32_t mmap_size, mclr_size, full_size, type_size;
    uint32_t rates[7];
    uint32_t pad;
    /* frame info */
    uint32_t *frm_size;
    uint8_t  *frm_flags;
    /* internal variables */
    int cur_frame;
    int is_ver4;
    int64_t cur_pts;
    /* current frame for demuxing */
    uint8_t pal[768];
    int indexes[7];
    int videoindex;
    uint8_t *bufs[7];
    int buf_sizes[7];
    int stream_id[7];
    int curstream;
    offset_t nextpos;
} SmackerContext;

typedef struct SmackerFrame {
    int64_t pts;
    int stream;
} SmackerFrame;

/* palette used in Smacker */
static const uint8_t smk_pal[64] = {
    0x00, 0x04, 0x08, 0x0C, 0x10, 0x14, 0x18, 0x1C,
    0x20, 0x24, 0x28, 0x2C, 0x30, 0x34, 0x38, 0x3C,
    0x41, 0x45, 0x49, 0x4D, 0x51, 0x55, 0x59, 0x5D,
    0x61, 0x65, 0x69, 0x6D, 0x71, 0x75, 0x79, 0x7D,
    0x82, 0x86, 0x8A, 0x8E, 0x92, 0x96, 0x9A, 0x9E,
    0xA2, 0xA6, 0xAA, 0xAE, 0xB2, 0xB6, 0xBA, 0xBE,
    0xC3, 0xC7, 0xCB, 0xCF, 0xD3, 0xD7, 0xDB, 0xDF,
    0xE3, 0xE7, 0xEB, 0xEF, 0xF3, 0xF7, 0xFB, 0xFF
};


static int smacker_probe(AVProbeData *p)
{
    if (p->buf_size < 4)
        return 0;
    if(p->buf[0] == 'S' && p->buf[1] == 'M' && p->buf[2] == 'K'
        && (p->buf[3] == '2' || p->buf[3] == '4'))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int smacker_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
    ByteIOContext *pb = &s->pb;
    SmackerContext *smk = (SmackerContext *)s->priv_data;
    AVStream *st, *ast[7];
    int i, ret;
    int tbase;

    /* read and check header */
    smk->magic = get_le32(pb);
    if (smk->magic != MKTAG('S', 'M', 'K', '2') && smk->magic != MKTAG('S', 'M', 'K', '4'))
        return -1;
    smk->width = get_le32(pb);
    smk->height = get_le32(pb);
    smk->frames = get_le32(pb);
    smk->pts_inc = (int32_t)get_le32(pb);
    smk->flags = get_le32(pb);
    for(i = 0; i < 7; i++)
        smk->audio[i] = get_le32(pb);
    smk->treesize = get_le32(pb);
    smk->mmap_size = get_le32(pb);
    smk->mclr_size = get_le32(pb);
    smk->full_size = get_le32(pb);
    smk->type_size = get_le32(pb);
    for(i = 0; i < 7; i++)
        smk->rates[i] = get_le32(pb);
    smk->pad = get_le32(pb);
    /* setup data */
    if(smk->frames > 0xFFFFFF) {
        av_log(s, AV_LOG_ERROR, "Too many frames: %i\n", smk->frames);
        return -1;
    }
    smk->frm_size = av_malloc(smk->frames * 4);
    smk->frm_flags = av_malloc(smk->frames);

    smk->is_ver4 = (smk->magic != MKTAG('S', 'M', 'K', '2'));

    /* read frame info */
    for(i = 0; i < smk->frames; i++) {
        smk->frm_size[i] = get_le32(pb);
    }
    for(i = 0; i < smk->frames; i++) {
        smk->frm_flags[i] = get_byte(pb);
    }

    /* init video codec */
    st = av_new_stream(s, 0);
    if (!st)
        return -1;
    smk->videoindex = st->index;
    st->codec->width = smk->width;
    st->codec->height = smk->height;
    st->codec->pix_fmt = PIX_FMT_PAL8;
    st->codec->codec_type = CODEC_TYPE_VIDEO;
    st->codec->codec_id = CODEC_ID_SMACKVIDEO;
    st->codec->codec_tag = smk->is_ver4;
    /* Smacker uses 100000 as internal timebase */
    if(smk->pts_inc < 0)
        smk->pts_inc = -smk->pts_inc;
    else
        smk->pts_inc *= 100;
    tbase = 100000;
    av_reduce(&tbase, &smk->pts_inc, tbase, smk->pts_inc, (1UL<<31)-1);
    av_set_pts_info(st, 33, smk->pts_inc, tbase);
    /* handle possible audio streams */
    for(i = 0; i < 7; i++) {
        smk->indexes[i] = -1;
        if((smk->rates[i] & 0xFFFFFF) && !(smk->rates[i] & SMK_AUD_BINKAUD)){
            ast[i] = av_new_stream(s, 0);
            smk->indexes[i] = ast[i]->index;
            av_set_pts_info(ast[i], 33, smk->pts_inc, tbase);
            ast[i]->codec->codec_type = CODEC_TYPE_AUDIO;
            ast[i]->codec->codec_id = (smk->rates[i] & SMK_AUD_PACKED) ? CODEC_ID_SMACKAUDIO : CODEC_ID_PCM_U8;
            ast[i]->codec->codec_tag = 0;
            ast[i]->codec->channels = (smk->rates[i] & SMK_AUD_STEREO) ? 2 : 1;
            ast[i]->codec->sample_rate = smk->rates[i] & 0xFFFFFF;
            ast[i]->codec->bits_per_sample = (smk->rates[i] & SMK_AUD_16BITS) ? 16 : 8;
            if(ast[i]->codec->bits_per_sample == 16 && ast[i]->codec->codec_id == CODEC_ID_PCM_U8)
                ast[i]->codec->codec_id = CODEC_ID_PCM_S16LE;
        }
    }


    /* load trees to extradata, they will be unpacked by decoder */
    st->codec->extradata = av_malloc(smk->treesize + 16);
    st->codec->extradata_size = smk->treesize + 16;
    if(!st->codec->extradata){
        av_log(s, AV_LOG_ERROR, "Cannot allocate %i bytes of extradata\n", smk->treesize + 16);
        av_free(smk->frm_size);
        av_free(smk->frm_flags);
        return -1;
    }
    ret = get_buffer(pb, st->codec->extradata + 16, st->codec->extradata_size - 16);
    if(ret != st->codec->extradata_size - 16){
        av_free(smk->frm_size);
        av_free(smk->frm_flags);
        return AVERROR_IO;
    }
    ((int32_t*)st->codec->extradata)[0] = le2me_32(smk->mmap_size);
    ((int32_t*)st->codec->extradata)[1] = le2me_32(smk->mclr_size);
    ((int32_t*)st->codec->extradata)[2] = le2me_32(smk->full_size);
    ((int32_t*)st->codec->extradata)[3] = le2me_32(smk->type_size);

    smk->curstream = -1;
    smk->nextpos = url_ftell(pb);

    return 0;
}


static int smacker_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    SmackerContext *smk = (SmackerContext *)s->priv_data;
    int flags;
    int ret;
    int i;
    int frame_size = 0;
    int palchange = 0;
    int pos;

    if (url_feof(&s->pb) || smk->cur_frame >= smk->frames)
        return -EIO;

    /* if we demuxed all streams, pass another frame */
    if(smk->curstream < 0) {
        url_fseek(&s->pb, smk->nextpos, 0);
        frame_size = smk->frm_size[smk->cur_frame] & (~3);
        flags = smk->frm_flags[smk->cur_frame];
        /* handle palette change event */
        pos = url_ftell(&s->pb);
        if(flags & SMACKER_PAL){
            int size, sz, t, off, j, pos;
            uint8_t *pal = smk->pal;
            uint8_t oldpal[768];

            memcpy(oldpal, pal, 768);
            size = get_byte(&s->pb);
            size = size * 4 - 1;
            frame_size -= size;
            frame_size--;
            sz = 0;
            pos = url_ftell(&s->pb) + size;
            while(sz < 256){
                t = get_byte(&s->pb);
                if(t & 0x80){ /* skip palette entries */
                    sz += (t & 0x7F) + 1;
                    pal += ((t & 0x7F) + 1) * 3;
                } else if(t & 0x40){ /* copy with offset */
                    off = get_byte(&s->pb) * 3;
                    j = (t & 0x3F) + 1;
                    while(j-- && sz < 256) {
                        *pal++ = oldpal[off + 0];
                        *pal++ = oldpal[off + 1];
                        *pal++ = oldpal[off + 2];
                        sz++;
                        off += 3;
                    }
                } else { /* new entries */
                    *pal++ = smk_pal[t];
                    *pal++ = smk_pal[get_byte(&s->pb) & 0x3F];
                    *pal++ = smk_pal[get_byte(&s->pb) & 0x3F];
                    sz++;
                }
            }
            url_fseek(&s->pb, pos, 0);
            palchange |= 1;
        }
        flags >>= 1;
        smk->curstream = -1;
        /* if audio chunks are present, put them to stack and retrieve later */
        for(i = 0; i < 7; i++) {
            if(flags & 1) {
                int size;
                size = get_le32(&s->pb) - 4;
                frame_size -= size;
                frame_size -= 4;
                smk->curstream++;
                smk->bufs[smk->curstream] = av_realloc(smk->bufs[smk->curstream], size);
                smk->buf_sizes[smk->curstream] = size;
                ret = get_buffer(&s->pb, smk->bufs[smk->curstream], size);
                if(ret != size)
                    return AVERROR_IO;
                smk->stream_id[smk->curstream] = smk->indexes[i];
            }
            flags >>= 1;
        }
        if (av_new_packet(pkt, frame_size + 768))
            return AVERROR_NOMEM;
        if(smk->frm_size[smk->cur_frame] & 1)
            palchange |= 2;
        pkt->data[0] = palchange;
        memcpy(pkt->data + 1, smk->pal, 768);
        ret = get_buffer(&s->pb, pkt->data + 769, frame_size);
        if(ret != frame_size)
            return AVERROR_IO;
        pkt->stream_index = smk->videoindex;
        pkt->size = ret + 769;
        smk->cur_frame++;
        smk->nextpos = url_ftell(&s->pb);
    } else {
        if (av_new_packet(pkt, smk->buf_sizes[smk->curstream]))
            return AVERROR_NOMEM;
        memcpy(pkt->data, smk->bufs[smk->curstream], smk->buf_sizes[smk->curstream]);
        pkt->size = smk->buf_sizes[smk->curstream];
        pkt->stream_index = smk->stream_id[smk->curstream];
        smk->curstream--;
    }

    return 0;
}

static int smacker_read_close(AVFormatContext *s)
{
    SmackerContext *smk = (SmackerContext *)s->priv_data;
    int i;

    for(i = 0; i < 7; i++)
        if(smk->bufs[i])
            av_free(smk->bufs[i]);
    if(smk->frm_size)
        av_free(smk->frm_size);
    if(smk->frm_flags)
        av_free(smk->frm_flags);

    for(i=0;i<s->nb_streams;i++) {
        AVStream *st = s->streams[i];
        if(st->codec->extradata)
            av_free(st->codec->extradata);
    }
    return 0;
}

static AVInputFormat smacker_iformat = {
    "smk",
    "Smacker Video",
    sizeof(SmackerContext),
    smacker_probe,
    smacker_read_header,
    smacker_read_packet,
    smacker_read_close,
};

int smacker_init(void)
{
    av_register_input_format(&smacker_iformat);
    return 0;
}