nsvdec.c

ffmpeg源码分析

/*
 * NSV decoder.
 * 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
 */
#include "avformat.h"
#include "avi.h"

#define DEBUG
//#define DEBUG_DUMP_INDEX // XXX dumbdriving-271.nsv breaks with it commented!!
//#define DEBUG_SEEK
#define CHECK_SUBSEQUENT_NSVS
//#define DISABLE_AUDIO

/* max bytes to crawl for trying to resync
 * stupid streaming servers don't start at chunk boundaries...
 */
#define NSV_MAX_RESYNC (500*1024)
#define NSV_MAX_RESYNC_TRIES 300

/*
 * First version by Francois Revol - [e-mail]
 * References:
 * (1) http://www.multimedia.cx/nsv-format.txt
 * seems someone came to the same conclusions as me, and updated it:
 * (2) http://www.stud.ktu.lt/~vitslav/nsv/nsv-format.txt
 *     http://www.stud.ktu.lt/~vitslav/nsv/
 * Sample files:
 * (S1) http://www.nullsoft.com/nsv/samples/
 * http://www.nullsoft.com/nsv/samples/faster.nsv
 * http://streamripper.sourceforge.net/openbb/read.php?TID=492&page=4
 */

/*
 * notes on the header (Francois Revol):
 *
 * It is followed by strings, then a table, but nothing tells
 * where the table begins according to (1). After checking faster.nsv,
 * I believe NVSf[16-19] gives the size of the strings data
 * (that is the offset of the data table after the header).
 * After checking all samples from (S1) all confirms this.
 *
 * Then, about NSVf[12-15], faster.nsf has 179700. When veiwing it in VLC,
 * I noticed there was about 1 NVSs chunk/s, so I ran
 * strings faster.nsv | grep NSVs | wc -l
 * which gave me 180. That leads me to think that NSVf[12-15] might be the
 * file length in milliseconds.
 * Let's try that:
 * for f in *.nsv; do HTIME="$(od -t x4 "$f" | head -1 | sed 's/.* //')"; echo "'$f' $((0x$HTIME))s = $((0x$HTIME/1000/60)):$((0x$HTIME/1000%60))"; done
 * except for nstrailer (which doesn't have an NSVf header), it repports correct time.
 *
 * nsvtrailer.nsv (S1) does not have any NSVf header, only NSVs chunks,
 * so the header seems to not be mandatory. (for streaming).
 *
 * index slice duration check (excepts nsvtrailer.nsv):
 * for f in [^n]*.nsv; do DUR="$(ffmpeg -i "$f" 2>/dev/null | grep 'NSVf duration' | cut -d ' ' -f 4)"; IC="$(ffmpeg -i "$f" 2>/dev/null | grep 'INDEX ENTRIES' | cut -d ' ' -f 2)"; echo "duration $DUR, slite time $(($DUR/$IC))"; done
 */

/*
 * TODO:
 * - handle timestamps !!!
 * - use index
 * - mime-type in probe()
 * - seek
 */

#ifdef DEBUG
#define PRINT(_v) printf _v
#else
#define PRINT(_v)
#endif

#if 0
struct NSVf_header {
    uint32_t chunk_tag; /* 'NSVf' */
    uint32_t chunk_size;
    uint32_t file_size; /* max 4GB ??? noone learns anything it seems :^) */
    uint32_t file_length; //unknown1;  /* what about MSB of file_size ? */
    uint32_t info_strings_size; /* size of the info strings */ //unknown2;
    uint32_t table_entries;
    uint32_t table_entries_used; /* the left ones should be -1 */
};

struct NSVs_header {
    uint32_t chunk_tag; /* 'NSVs' */
    uint32_t v4cc;      /* or 'NONE' */
    uint32_t a4cc;      /* or 'NONE' */
    uint16_t vwidth;    /* assert(vwidth%16==0) */
    uint16_t vheight;   /* assert(vheight%16==0) */
    uint8_t framerate;  /* value = (framerate&0x80)?frtable[frameratex0x7f]:framerate */
    uint16_t unknown;
};

struct nsv_avchunk_header {
    uint8_t vchunk_size_lsb;
    uint16_t vchunk_size_msb; /* value = (vchunk_size_msb << 4) | (vchunk_size_lsb >> 4) */
    uint16_t achunk_size;
};

struct nsv_pcm_header {
    uint8_t bits_per_sample;
    uint8_t channel_count;
    uint16_t sample_rate;
};
#endif

/* variation from avi.h */
/*typedef struct CodecTag {
    int id;
    unsigned int tag;
} CodecTag;*/

/* tags */

#define T_NSVF MKTAG('N', 'S', 'V', 'f') /* file header */
#define T_NSVS MKTAG('N', 'S', 'V', 's') /* chunk header */
#define T_TOC2 MKTAG('T', 'O', 'C', '2') /* extra index marker */
#define T_NONE MKTAG('N', 'O', 'N', 'E') /* null a/v 4CC */
#define T_SUBT MKTAG('S', 'U', 'B', 'T') /* subtitle aux data */
#define T_ASYN MKTAG('A', 'S', 'Y', 'N') /* async a/v aux marker */
#define T_KEYF MKTAG('K', 'E', 'Y', 'F') /* video keyframe aux marker (addition) */

#define TB_NSVF MKBETAG('N', 'S', 'V', 'f')
#define TB_NSVS MKBETAG('N', 'S', 'V', 's')

/* hardcoded stream indices */
#define NSV_ST_VIDEO 0
#define NSV_ST_AUDIO 1
#define NSV_ST_SUBT 2

enum NSVStatus {
    NSV_UNSYNC,
    NSV_FOUND_NSVF,
    NSV_HAS_READ_NSVF,
    NSV_FOUND_NSVS,
    NSV_HAS_READ_NSVS,
    NSV_FOUND_BEEF,
    NSV_GOT_VIDEO,
    NSV_GOT_AUDIO,
};

typedef struct NSVStream {
    int frame_offset; /* current frame (video) or byte (audio) counter
                         (used to compute the pts) */
    int scale;
    int rate;
    int sample_size; /* audio only data */
    int start;

    int new_frame_offset; /* temporary storage (used during seek) */
    int cum_len; /* temporary storage (used during seek) */
} NSVStream;

typedef struct {
    int  base_offset;
    int  NSVf_end;
    uint32_t *nsvf_index_data;
    int index_entries;
    enum NSVStatus state;
    AVPacket ahead[2]; /* [v, a] if .data is !NULL there is something */
    /* cached */
    int64_t duration;
    uint32_t vtag, atag;
    uint16_t vwidth, vheight;
    //DVDemuxContext* dv_demux;
} NSVContext;

static const CodecTag nsv_codec_video_tags[] = {
    { CODEC_ID_VP3, MKTAG('V', 'P', '3', ' ') },
    { CODEC_ID_VP3, MKTAG('V', 'P', '3', '0') },
    { CODEC_ID_VP3, MKTAG('V', 'P', '3', '1') },
/*
    { CODEC_ID_VP4, MKTAG('V', 'P', '4', ' ') },
    { CODEC_ID_VP4, MKTAG('V', 'P', '4', '0') },
    { CODEC_ID_VP5, MKTAG('V', 'P', '5', ' ') },
    { CODEC_ID_VP5, MKTAG('V', 'P', '5', '0') },
    { CODEC_ID_VP6, MKTAG('V', 'P', '6', ' ') },
    { CODEC_ID_VP6, MKTAG('V', 'P', '6', '0') },
    { CODEC_ID_VP6, MKTAG('V', 'P', '6', '1') },
    { CODEC_ID_VP6, MKTAG('V', 'P', '6', '2') },
*/
    { CODEC_ID_XVID, MKTAG('X', 'V', 'I', 'D') }, /* cf sample xvid decoder from nsv_codec_sdk.zip */
    { CODEC_ID_RAWVIDEO, MKTAG('R', 'G', 'B', '3') },
    { 0, 0 },
};

static const CodecTag nsv_codec_audio_tags[] = {
    { CODEC_ID_MP3, MKTAG('M', 'P', '3', ' ') },
    { CODEC_ID_AAC, MKTAG('A', 'A', 'C', ' ') },
    { CODEC_ID_AAC, MKTAG('A', 'A', 'C', 'P') }, /* _CUTTED__MUXED_2 Heads - Out Of The City.nsv */
    { CODEC_ID_PCM_U16LE, MKTAG('P', 'C', 'M', ' ') },
    { 0, 0 },
};

static const AVRational nsv_framerate_table[] = {
    {30,1},
    {30000,1001},
    {25,1},
    {24000,1001},
    {30,1},
    {15000,1001},
};

//static int nsv_load_index(AVFormatContext *s);
static int nsv_read_chunk(AVFormatContext *s, int fill_header);

#ifdef DEBUG
static void print_tag(const char *str, unsigned int tag, int size)
{
    printf("%s: tag=%c%c%c%c\n",
           str, tag & 0xff,
           (tag >> 8) & 0xff,
           (tag >> 16) & 0xff,
           (tag >> 24) & 0xff);
}
#endif

/* try to find something we recognize, and set the state accordingly */
static int nsv_resync(AVFormatContext *s)
{
    NSVContext *nsv = s->priv_data;
    ByteIOContext *pb = &s->pb;
    uint32_t v = 0;
    int i;

    PRINT(("%s(), offset = %"PRId64", state = %d\n", __FUNCTION__, url_ftell(pb), nsv->state));

    //nsv->state = NSV_UNSYNC;

    for (i = 0; i < NSV_MAX_RESYNC; i++) {
        if (url_feof(pb)) {
            PRINT(("NSV EOF\n"));
            nsv->state = NSV_UNSYNC;
            return -1;
        }
        v <<= 8;
        v |= get_byte(pb);
/*
        if (i < 8) {
            PRINT(("NSV resync: [%d] = %02x\n", i, v & 0x0FF));
        }
*/

        if ((v & 0x0000ffff) == 0xefbe) { /* BEEF */
            PRINT(("NSV resynced on BEEF after %d bytes\n", i+1));
            nsv->state = NSV_FOUND_BEEF;
            return 0;
        }
        /* we read as big endian, thus the MK*BE* */
        if (v == TB_NSVF) { /* NSVf */
            PRINT(("NSV resynced on NSVf after %d bytes\n", i+1));
            nsv->state = NSV_FOUND_NSVF;
            return 0;
        }
        if (v == MKBETAG('N', 'S', 'V', 's')) { /* NSVs */
            PRINT(("NSV resynced on NSVs after %d bytes\n", i+1));
            nsv->state = NSV_FOUND_NSVS;
            return 0;
        }

    }
    PRINT(("NSV sync lost\n"));
    return -1;
}

static int nsv_parse_NSVf_header(AVFormatContext *s, AVFormatParameters *ap)
{
    NSVContext *nsv = s->priv_data;
    ByteIOContext *pb = &s->pb;
    unsigned int file_size, size;
    int64_t duration;
    int strings_size;
    int table_entries;
    int table_entries_used;

    PRINT(("%s()\n", __FUNCTION__));

    nsv->state = NSV_UNSYNC; /* in case we fail */

    size = get_le32(pb);
    if (size < 28)
        return -1;
    nsv->NSVf_end = size;

    //s->file_size = (uint32_t)get_le32(pb);
    file_size = (uint32_t)get_le32(pb);
    PRINT(("NSV NSVf chunk_size %u\n", size));
    PRINT(("NSV NSVf file_size %u\n", file_size));

    nsv->duration = duration = get_le32(pb); /* in ms */
    PRINT(("NSV NSVf duration %"PRId64" ms\n", duration));
    // XXX: store it in AVStreams

    strings_size = get_le32(pb);
    table_entries = get_le32(pb);
    table_entries_used = get_le32(pb);
    PRINT(("NSV NSVf info-strings size: %d, table entries: %d, bis %d\n",
            strings_size, table_entries, table_entries_used));
    if (url_feof(pb))
        return -1;

    PRINT(("NSV got header; filepos %"PRId64"\n", url_ftell(pb)));

    if (strings_size > 0) {
        char *strings; /* last byte will be '\0' to play safe with str*() */
        char *p, *endp;
        char *token, *value;
        char quote;

        p = strings = av_mallocz(strings_size + 1);
        endp = strings + strings_size;
        get_buffer(pb, strings, strings_size);
        while (p < endp) {
            while (*p == ' ')
                p++; /* strip out spaces */
            if (p >= endp-2)
                break;
            token = p;
            p = strchr(p, '=');
            if (!p || p >= endp-2)
                break;
            *p++ = '\0';
            quote = *p++;
            value = p;
            p = strchr(p, quote);
            if (!p || p >= endp)
                break;
            *p++ = '\0';
            PRINT(("NSV NSVf INFO: %s='%s'\n", token, value));
            if (!strcmp(token, "ASPECT")) {
                /* don't care */
            } else if (!strcmp(token, "CREATOR") || !strcmp(token, "Author")) {
                strncpy(s->author, value, 512-1);
            } else if (!strcmp(token, "Copyright")) {
                strncpy(s->copyright, value, 512-1);
            } else if (!strcmp(token, "TITLE") || !strcmp(token, "Title")) {
                strncpy(s->title, value, 512-1);
            }
        }
        av_free(strings);
    }
    if (url_feof(pb))
        return -1;

    PRINT(("NSV got infos; filepos %"PRId64"\n", url_ftell(pb)));

    if (table_entries_used > 0) {
        nsv->index_entries = table_entries_used;
        if((unsigned)table_entries >= UINT_MAX / sizeof(uint32_t))
            return -1;
        nsv->nsvf_index_data = av_malloc(table_entries * sizeof(uint32_t));
#warning "FIXME: Byteswap buffer as needed"
        get_buffer(pb, (unsigned char *)nsv->nsvf_index_data, table_entries * sizeof(uint32_t));
    }

    PRINT(("NSV got index; filepos %"PRId64"\n", url_ftell(pb)));

#ifdef DEBUG_DUMP_INDEX
#define V(v) ((v<0x20 || v > 127)?'.':v)
    /* dump index */
    PRINT(("NSV %d INDEX ENTRIES:\n", table_entries));
    PRINT(("NSV [dataoffset][fileoffset]\n", table_entries));
    for (i = 0; i < table_entries; i++) {
        unsigned char b[8];
        url_fseek(pb, size + nsv->nsvf_index_data[i], SEEK_SET);
        get_buffer(pb, b, 8);
        PRINT(("NSV [0x%08lx][0x%08lx]: %02x %02x %02x %02x %02x %02x %02x %02x"
           "%c%c%c%c%c%c%c%c\n",