ipmovie.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * Interplay MVE File Demuxer
 * Copyright (c) 2003 The ffmpeg Project
 *
 * 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
 */

/**
 * @file ipmovie.c
 * Interplay MVE file demuxer
 * by Mike Melanson ([e-mail])
 * For more information regarding the Interplay MVE file format, visit:
 *   http://www.pcisys.net/~melanson/codecs/
 * The aforementioned site also contains a command line utility for parsing
 * IP MVE files so that you can get a good idea of the typical structure of
 * such files. This demuxer is not the best example to use if you are trying
 * to write your own as it uses a rather roundabout approach for splitting
 * up and sending out the chunks.
 */

#include "avformat.h"

/* debugging support: #define DEBUG_IPMOVIE as non-zero to see extremely
 * verbose information about the demux process */
#define DEBUG_IPMOVIE 0

#if DEBUG_IPMOVIE
#define debug_ipmovie printf
#else
static inline void debug_ipmovie(const char *format, ...) { }
#endif

#define IPMOVIE_SIGNATURE "Interplay MVE File\x1A\0"
#define IPMOVIE_SIGNATURE_SIZE 20
#define CHUNK_PREAMBLE_SIZE 4
#define OPCODE_PREAMBLE_SIZE 4

#define CHUNK_INIT_AUDIO   0x0000
#define CHUNK_AUDIO_ONLY   0x0001
#define CHUNK_INIT_VIDEO   0x0002
#define CHUNK_VIDEO        0x0003
#define CHUNK_SHUTDOWN     0x0004
#define CHUNK_END          0x0005
/* these last types are used internally */
#define CHUNK_DONE         0xFFFC
#define CHUNK_NOMEM        0xFFFD
#define CHUNK_EOF          0xFFFE
#define CHUNK_BAD          0xFFFF

#define OPCODE_END_OF_STREAM           0x00
#define OPCODE_END_OF_CHUNK            0x01
#define OPCODE_CREATE_TIMER            0x02
#define OPCODE_INIT_AUDIO_BUFFERS      0x03
#define OPCODE_START_STOP_AUDIO        0x04
#define OPCODE_INIT_VIDEO_BUFFERS      0x05
#define OPCODE_UNKNOWN_06              0x06
#define OPCODE_SEND_BUFFER             0x07
#define OPCODE_AUDIO_FRAME             0x08
#define OPCODE_SILENCE_FRAME           0x09
#define OPCODE_INIT_VIDEO_MODE         0x0A
#define OPCODE_CREATE_GRADIENT         0x0B
#define OPCODE_SET_PALETTE             0x0C
#define OPCODE_SET_PALETTE_COMPRESSED  0x0D
#define OPCODE_UNKNOWN_0E              0x0E
#define OPCODE_SET_DECODING_MAP        0x0F
#define OPCODE_UNKNOWN_10              0x10
#define OPCODE_VIDEO_DATA              0x11
#define OPCODE_UNKNOWN_12              0x12
#define OPCODE_UNKNOWN_13              0x13
#define OPCODE_UNKNOWN_14              0x14
#define OPCODE_UNKNOWN_15              0x15

#define PALETTE_COUNT 256

typedef struct IPMVEContext {

    unsigned char *buf;
    int buf_size;

    float fps;
    int frame_pts_inc;

    unsigned int video_width;
    unsigned int video_height;
    int64_t video_pts;

    unsigned int audio_bits;
    unsigned int audio_channels;
    unsigned int audio_sample_rate;
    unsigned int audio_type;
    unsigned int audio_frame_count;

    int video_stream_index;
    int audio_stream_index;

    offset_t audio_chunk_offset;
    int audio_chunk_size;
    offset_t video_chunk_offset;
    int video_chunk_size;
    offset_t decode_map_chunk_offset;
    int decode_map_chunk_size;

    offset_t next_chunk_offset;

    AVPaletteControl palette_control;

} IPMVEContext;

static int load_ipmovie_packet(IPMVEContext *s, ByteIOContext *pb,
    AVPacket *pkt) {

    int chunk_type;
    int64_t audio_pts = 0;

    if (s->audio_chunk_offset) {

        /* adjust for PCM audio by skipping chunk header */
        if (s->audio_type != CODEC_ID_INTERPLAY_DPCM) {
            s->audio_chunk_offset += 6;
            s->audio_chunk_size -= 6;
        }

        url_fseek(pb, s->audio_chunk_offset, SEEK_SET);
        s->audio_chunk_offset = 0;

        /* figure out the audio pts */
        audio_pts = 90000;
        audio_pts *= s->audio_frame_count;
        audio_pts /= s->audio_sample_rate;

        if (s->audio_chunk_size != av_get_packet(pb, pkt, s->audio_chunk_size))
            return CHUNK_EOF;

        pkt->stream_index = s->audio_stream_index;
        pkt->pts = audio_pts;

        /* audio frame maintenance */
        if (s->audio_type != CODEC_ID_INTERPLAY_DPCM)
            s->audio_frame_count +=
            (s->audio_chunk_size / s->audio_channels / (s->audio_bits / 8));
        else
            s->audio_frame_count +=
                (s->audio_chunk_size - 6) / s->audio_channels;

        debug_ipmovie("sending audio frame with pts %"PRId64" (%d audio frames)\n",
            audio_pts, s->audio_frame_count);

        chunk_type = CHUNK_VIDEO;

    } else if (s->decode_map_chunk_offset) {

        /* send both the decode map and the video data together */

        if (av_new_packet(pkt, s->decode_map_chunk_size + s->video_chunk_size))
            return CHUNK_NOMEM;

        pkt->pos= s->decode_map_chunk_offset;
        url_fseek(pb, s->decode_map_chunk_offset, SEEK_SET);
        s->decode_map_chunk_offset = 0;

        if (get_buffer(pb, pkt->data, s->decode_map_chunk_size) !=
            s->decode_map_chunk_size) {
            av_free_packet(pkt);
            return CHUNK_EOF;
        }

        url_fseek(pb, s->video_chunk_offset, SEEK_SET);
        s->video_chunk_offset = 0;

        if (get_buffer(pb, pkt->data + s->decode_map_chunk_size,
            s->video_chunk_size) != s->video_chunk_size) {
            av_free_packet(pkt);
            return CHUNK_EOF;
        }

        pkt->stream_index = s->video_stream_index;
        pkt->pts = s->video_pts;

        debug_ipmovie("sending video frame with pts %"PRId64"\n",
            pkt->pts);

        s->video_pts += s->frame_pts_inc;

        chunk_type = CHUNK_VIDEO;

    } else {

        url_fseek(pb, s->next_chunk_offset, SEEK_SET);
        chunk_type = CHUNK_DONE;

    }

    return chunk_type;
}

/* This function loads and processes a single chunk in an IP movie file.
 * It returns the type of chunk that was processed. */
static int process_ipmovie_chunk(IPMVEContext *s, ByteIOContext *pb,
    AVPacket *pkt)
{
    unsigned char chunk_preamble[CHUNK_PREAMBLE_SIZE];
    int chunk_type;
    int chunk_size;
    unsigned char opcode_preamble[OPCODE_PREAMBLE_SIZE];
    unsigned char opcode_type;
    unsigned char opcode_version;
    int opcode_size;
    unsigned char scratch[1024];
    int i, j;
    int first_color, last_color;
    int audio_flags;
    unsigned char r, g, b;

    /* see if there are any pending packets */
    chunk_type = load_ipmovie_packet(s, pb, pkt);
    if (chunk_type != CHUNK_DONE)
        return chunk_type;

    /* read the next chunk, wherever the file happens to be pointing */
    if (url_feof(pb))
        return CHUNK_EOF;
    if (get_buffer(pb, chunk_preamble, CHUNK_PREAMBLE_SIZE) !=
        CHUNK_PREAMBLE_SIZE)
        return CHUNK_BAD;
    chunk_size = AV_RL16(&chunk_preamble[0]);
    chunk_type = AV_RL16(&chunk_preamble[2]);

    debug_ipmovie("chunk type 0x%04X, 0x%04X bytes: ", chunk_type, chunk_size);

    switch (chunk_type) {

    case CHUNK_INIT_AUDIO:
        debug_ipmovie("initialize audio\n");
        break;

    case CHUNK_AUDIO_ONLY:
        debug_ipmovie("audio only\n");
        break;

    case CHUNK_INIT_VIDEO:
        debug_ipmovie("initialize video\n");
        break;

    case CHUNK_VIDEO:
        debug_ipmovie("video (and audio)\n");
        break;

    case CHUNK_SHUTDOWN:
        debug_ipmovie("shutdown\n");
        break;

    case CHUNK_END:
        debug_ipmovie("end\n");
        break;

    default:
        debug_ipmovie("invalid chunk\n");
        chunk_type = CHUNK_BAD;
        break;

    }

    while ((chunk_size > 0) && (chunk_type != CHUNK_BAD)) {

        /* read the next chunk, wherever the file happens to be pointing */
       if (url_feof(pb)) {
            chunk_type = CHUNK_EOF;
            break;
        }
        if (get_buffer(pb, opcode_preamble, CHUNK_PREAMBLE_SIZE) !=
            CHUNK_PREAMBLE_SIZE) {
            chunk_type = CHUNK_BAD;
            break;
        }

        opcode_size = AV_RL16(&opcode_preamble[0]);
        opcode_type = opcode_preamble[2];
        opcode_version = opcode_preamble[3];

        chunk_size -= OPCODE_PREAMBLE_SIZE;
        chunk_size -= opcode_size;
        if (chunk_size < 0) {
            debug_ipmovie("chunk_size countdown just went negative\n");
            chunk_type = CHUNK_BAD;
            break;
        }

        debug_ipmovie("  opcode type %02X, version %d, 0x%04X bytes: ",
            opcode_type, opcode_version, opcode_size);
        switch (opcode_type) {

        case OPCODE_END_OF_STREAM:
            debug_ipmovie("end of stream\n");
            url_fseek(pb, opcode_size, SEEK_CUR);
            break;

        case OPCODE_END_OF_CHUNK:
            debug_ipmovie("end of chunk\n");
            url_fseek(pb, opcode_size, SEEK_CUR);