decode.c

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/*
 * decode.c
 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
 *
 * This file is part of mpeg2dec, a free MPEG-2 video stream decoder.
 * See http://libmpeg2.sourceforge.net/ for updates.
 *
 * mpeg2dec is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpeg2dec 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "config.h"

#include <string.h>     /* memcmp/memset, try to remove */
#include <stdlib.h>
#include <inttypes.h>

#include "mpeg2.h"
#include "attributes.h"
#include "mpeg2_internal.h"

static int mpeg2_accels = 0;

#define BUFFER_SIZE (1194 * 1024)

const mpeg2_info_t * mpeg2_info (mpeg2dec_t * mpeg2dec)
{
    return &(mpeg2dec->info);
}

static inline int skip_chunk (mpeg2dec_t * mpeg2dec, int bytes)
{
    uint8_t * current;
    uint32_t shift;
    uint8_t * limit;
    uint8_t byte;

    if (!bytes)
        return 0;

    current = mpeg2dec->buf_start;
    shift = mpeg2dec->shift;
    limit = current + bytes;

    do {
        byte = *current++;
        if (shift == 0x00000100) {
            int skipped;

            mpeg2dec->shift = 0xffffff00;
            skipped = current - mpeg2dec->buf_start;
            mpeg2dec->buf_start = current;
            return skipped;
        }
        shift = (shift | byte) << 8;
    } while (current < limit);

    mpeg2dec->shift = shift;
    mpeg2dec->buf_start = current;
    return 0;
}

static inline int copy_chunk (mpeg2dec_t * mpeg2dec, int bytes)
{
    uint8_t * current;
    uint32_t shift;
    uint8_t * chunk_ptr;
    uint8_t * limit;
    uint8_t byte;

    if (!bytes)
        return 0;

    current = mpeg2dec->buf_start;
    shift = mpeg2dec->shift;
    chunk_ptr = mpeg2dec->chunk_ptr;
    limit = current + bytes;

    do {
        byte = *current++;
        if (shift == 0x00000100) {
            int copied;

            mpeg2dec->shift = 0xffffff00;
            mpeg2dec->chunk_ptr = chunk_ptr + 1;
            copied = current - mpeg2dec->buf_start;
            mpeg2dec->buf_start = current;
            return copied;
        }
        shift = (shift | byte) << 8;
        *chunk_ptr++ = byte;
    } while (current < limit);

    mpeg2dec->shift = shift;
    mpeg2dec->buf_start = current;
    return 0;
}

void mpeg2_buffer (mpeg2dec_t * mpeg2dec, uint8_t * start, uint8_t * end)
{
    mpeg2dec->buf_start = start;
    mpeg2dec->buf_end = end;
}

int mpeg2_getpos (mpeg2dec_t * mpeg2dec)
{
    return mpeg2dec->buf_end - mpeg2dec->buf_start;
}

static inline mpeg2_state_t seek_chunk (mpeg2dec_t * mpeg2dec)
{
    int size, skipped;

    size = mpeg2dec->buf_end - mpeg2dec->buf_start;
    skipped = skip_chunk (mpeg2dec, size);
    if (!skipped) {
        mpeg2dec->bytes_since_tag += size;
        return STATE_BUFFER;
    }
    mpeg2dec->bytes_since_tag += skipped;
    mpeg2dec->code = mpeg2dec->buf_start[-1];
    return STATE_INTERNAL_NORETURN;
}

mpeg2_state_t mpeg2_seek_header (mpeg2dec_t * mpeg2dec)
{
    while (!(mpeg2dec->code == 0xb3 ||
             ((mpeg2dec->code == 0xb7 || mpeg2dec->code == 0xb8 ||
               !mpeg2dec->code) && mpeg2dec->sequence.width != (unsigned)-1)))
        if (seek_chunk (mpeg2dec) == STATE_BUFFER)
            return STATE_BUFFER;
    mpeg2dec->chunk_start = mpeg2dec->chunk_ptr = mpeg2dec->chunk_buffer;
    mpeg2dec->user_data_len = 0;
    return ((mpeg2dec->code == 0xb7) ?
            mpeg2_header_end (mpeg2dec) : mpeg2_parse_header (mpeg2dec));
}

#define RECEIVED(code,state) (((state) << 8) + (code))

mpeg2_state_t mpeg2_parse (mpeg2dec_t * mpeg2dec)
{
    int size_buffer, size_chunk, copied;

    if (mpeg2dec->action) {
        mpeg2_state_t state;

        state = mpeg2dec->action (mpeg2dec);
        if ((int)state > (int)STATE_INTERNAL_NORETURN)
            return state;
    }

    while (1) {
        while ((unsigned) (mpeg2dec->code - mpeg2dec->first_decode_slice) <
               mpeg2dec->nb_decode_slices) {
            size_buffer = mpeg2dec->buf_end - mpeg2dec->buf_start;
            size_chunk = (mpeg2dec->chunk_buffer + BUFFER_SIZE -
                          mpeg2dec->chunk_ptr);
            if (size_buffer <= size_chunk) {
                copied = copy_chunk (mpeg2dec, size_buffer);
                if (!copied) {
                    mpeg2dec->bytes_since_tag += size_buffer;
                    mpeg2dec->chunk_ptr += size_buffer;
                    return STATE_BUFFER;
                }
            } else {
                copied = copy_chunk (mpeg2dec, size_chunk);
                if (!copied) {
                    /* filled the chunk buffer without finding a start code */
                    mpeg2dec->bytes_since_tag += size_chunk;
                    mpeg2dec->action = seek_chunk;
                    return STATE_INVALID;
                }
            }
            mpeg2dec->bytes_since_tag += copied;

            mpeg2_slice (&(mpeg2dec->decoder), mpeg2dec->code,
                         mpeg2dec->chunk_start);
            mpeg2dec->code = mpeg2dec->buf_start[-1];
            mpeg2dec->chunk_ptr = mpeg2dec->chunk_start;
        }
        if ((unsigned) (mpeg2dec->code - 1) >= 0xb0 - 1)
            break;
        if (seek_chunk (mpeg2dec) == STATE_BUFFER)
            return STATE_BUFFER;
    }

    mpeg2dec->action = mpeg2_seek_header;
    switch (mpeg2dec->code) {
    case 0x00:
        return mpeg2dec->state;
    case 0xb3:
    case 0xb7:
    case 0xb8:
        return (mpeg2dec->state == STATE_SLICE) ? STATE_SLICE : STATE_INVALID;
    default:
        mpeg2dec->action = seek_chunk;
        return STATE_INVALID;
    }
}

mpeg2_state_t mpeg2_parse_header (mpeg2dec_t * mpeg2dec)
{
    static int (* process_header[]) (mpeg2dec_t * mpeg2dec) = {
        mpeg2_header_picture, mpeg2_header_extension, mpeg2_header_user_data,
        mpeg2_header_sequence, NULL, NULL, NULL, NULL, mpeg2_header_gop
    };
    int size_buffer, size_chunk, copied;

    mpeg2dec->action = mpeg2_parse_header;
    mpeg2dec->info.user_data = NULL;    mpeg2dec->info.user_data_len = 0;
    while (1) {
        size_buffer = mpeg2dec->buf_end - mpeg2dec->buf_start;
        size_chunk = (mpeg2dec->chunk_buffer + BUFFER_SIZE -
                      mpeg2dec->chunk_ptr);
        if (size_buffer <= size_chunk) {
            copied = copy_chunk (mpeg2dec, size_buffer);
            if (!copied) {
                mpeg2dec->bytes_since_tag += size_buffer;
                mpeg2dec->chunk_ptr += size_buffer;
                return STATE_BUFFER;
            }
        } else {
            copied = copy_chunk (mpeg2dec, size_chunk);
            if (!copied) {
                /* filled the chunk buffer without finding a start code */
                mpeg2dec->bytes_since_tag += size_chunk;
                mpeg2dec->code = 0xb4;
                mpeg2dec->action = mpeg2_seek_header;
                return STATE_INVALID;
            }
        }
        mpeg2dec->bytes_since_tag += copied;

        if (process_header[mpeg2dec->code & 0x0b] (mpeg2dec)) {
            mpeg2dec->code = mpeg2dec->buf_start[-1];
            mpeg2dec->action = mpeg2_seek_header;
            return STATE_INVALID;
        }

        mpeg2dec->code = mpeg2dec->buf_start[-1];
        switch (RECEIVED (mpeg2dec->code, mpeg2dec->state)) {

        /* state transition after a sequence header */
        case RECEIVED (0x00, STATE_SEQUENCE):
        case RECEIVED (0xb8, STATE_SEQUENCE):
            mpeg2_header_sequence_finalize (mpeg2dec);
            break;

        /* other legal state transitions */
        case RECEIVED (0x00, STATE_GOP):
            mpeg2_header_gop_finalize (mpeg2dec);
            break;
        case RECEIVED (0x01, STATE_PICTURE):
        case RECEIVED (0x01, STATE_PICTURE_2ND):
            mpeg2_header_picture_finalize (mpeg2dec, mpeg2_accels);
            mpeg2dec->action = mpeg2_header_slice_start;
            break;

        /* legal headers within a given state */
        case RECEIVED (0xb2, STATE_SEQUENCE):
        case RECEIVED (0xb2, STATE_GOP):
        case RECEIVED (0xb2, STATE_PICTURE):
        case RECEIVED (0xb2, STATE_PICTURE_2ND):
        case RECEIVED (0xb5, STATE_SEQUENCE):
        case RECEIVED (0xb5, STATE_PICTURE):
        case RECEIVED (0xb5, STATE_PICTURE_2ND):
            mpeg2dec->chunk_ptr = mpeg2dec->chunk_start;
            continue;

        default:
            mpeg2dec->action = mpeg2_seek_header;
            return STATE_INVALID;
        }

        mpeg2dec->chunk_start = mpeg2dec->chunk_ptr = mpeg2dec->chunk_buffer;
        mpeg2dec->user_data_len = 0;
        return mpeg2dec->state;
    }
}

int mpeg2_convert (mpeg2dec_t * mpeg2dec, mpeg2_convert_t convert, void * arg)
{
    mpeg2_convert_init_t convert_init;
    int error;

    error = convert (MPEG2_CONVERT_SET, NULL, &(mpeg2dec->sequence), 0,
                     mpeg2_accels, arg, &convert_init);
    if (!error) {
        mpeg2dec->convert = convert;
        mpeg2dec->convert_arg = arg;
        mpeg2dec->convert_id_size = convert_init.id_size;
        mpeg2dec->convert_stride = 0;
    }
    return error;
}

int mpeg2_stride (mpeg2dec_t * mpeg2dec, int stride)
{
    if (!mpeg2dec->convert) {
        if (stride < (int) mpeg2dec->sequence.width)
            stride = mpeg2dec->sequence.width;
        mpeg2dec->decoder.stride_frame = stride;
    } else {
        mpeg2_convert_init_t convert_init;

        stride = mpeg2dec->convert (MPEG2_CONVERT_STRIDE, NULL,
                                    &(mpeg2dec->sequence), stride,
                                    mpeg2_accels, mpeg2dec->convert_arg,
                                    &convert_init);
        mpeg2dec->convert_id_size = convert_init.id_size;
        mpeg2dec->convert_stride = stride;
    }
    return stride;
}

void mpeg2_set_buf (mpeg2dec_t * mpeg2dec, uint8_t * buf[3], void * id)
{
    mpeg2_fbuf_t * fbuf;

    if (mpeg2dec->custom_fbuf) {
        if (mpeg2dec->state == STATE_SEQUENCE) {
            mpeg2dec->fbuf[2] = mpeg2dec->fbuf[1];
            mpeg2dec->fbuf[1] = mpeg2dec->fbuf[0];
        }
        mpeg2_set_fbuf (mpeg2dec, (mpeg2dec->decoder.coding_type ==
                                   PIC_FLAG_CODING_TYPE_B));
        fbuf = mpeg2dec->fbuf[0];
    } else {
        fbuf = &(mpeg2dec->fbuf_alloc[mpeg2dec->alloc_index].fbuf);
        mpeg2dec->alloc_index_user = ++mpeg2dec->alloc_index;
    }
    fbuf->buf[0] = buf[0];
    fbuf->buf[1] = buf[1];
    fbuf->buf[2] = buf[2];
    fbuf->id = id;
}

void mpeg2_custom_fbuf (mpeg2dec_t * mpeg2dec, int custom_fbuf)
{
    mpeg2dec->custom_fbuf = custom_fbuf;
}

void mpeg2_skip (mpeg2dec_t * mpeg2dec, int skip)
{
    mpeg2dec->first_decode_slice = 1;
    mpeg2dec->nb_decode_slices = skip ? 0 : (0xb0 - 1);
}

void mpeg2_slice_region (mpeg2dec_t * mpeg2dec, int start, int end)
{
    start = (start < 1) ? 1 : (start > 0xb0) ? 0xb0 : start;
    end = (end < start) ? start : (end > 0xb0) ? 0xb0 : end;
    mpeg2dec->first_decode_slice = start;
    mpeg2dec->nb_decode_slices = end - start;
}

void mpeg2_tag_picture (mpeg2dec_t * mpeg2dec, uint32_t tag, uint32_t tag2)
{
    mpeg2dec->tag_previous = mpeg2dec->tag_current;
    mpeg2dec->tag2_previous = mpeg2dec->tag2_current;
    mpeg2dec->tag_current = tag;
    mpeg2dec->tag2_current = tag2;
    mpeg2dec->num_tags++;
    mpeg2dec->bytes_since_tag = 0;
}

uint32_t mpeg2_accel (uint32_t accel)
{
    if (!mpeg2_accels) {
        mpeg2_accels = mpeg2_detect_accel (accel) | MPEG2_ACCEL_DETECT;
        mpeg2_cpu_state_init (mpeg2_accels);
        mpeg2_idct_init (mpeg2_accels);
        mpeg2_mc_init (mpeg2_accels);
    }
    return mpeg2_accels & ~MPEG2_ACCEL_DETECT;
}

void mpeg2_reset (mpeg2dec_t * mpeg2dec, int full_reset)
{
    mpeg2dec->buf_start = mpeg2dec->buf_end = NULL;
    mpeg2dec->num_tags = 0;
    mpeg2dec->shift = 0xffffff00;
    mpeg2dec->code = 0xb4;
    mpeg2dec->action = mpeg2_seek_header;
    mpeg2dec->state = STATE_INVALID;
    mpeg2dec->first = 1;

    mpeg2_reset_info(&(mpeg2dec->info));
    mpeg2dec->info.gop = NULL;
    mpeg2dec->info.user_data = NULL;
    mpeg2dec->info.user_data_len = 0;
    if (full_reset) {
        mpeg2dec->info.sequence = NULL;
        mpeg2_header_state_init (mpeg2dec);
    }

}

mpeg2dec_t * mpeg2_init (void)
{
    mpeg2dec_t * mpeg2dec;

    mpeg2_accel (MPEG2_ACCEL_DETECT);

    mpeg2dec = (mpeg2dec_t *) mpeg2_malloc (sizeof (mpeg2dec_t),
                                            MPEG2_ALLOC_MPEG2DEC);
    if (mpeg2dec == NULL)
        return NULL;

    memset (mpeg2dec->decoder.DCTblock, 0, 64 * sizeof (int16_t));
    memset (mpeg2dec->quantizer_matrix, 0, 4 * 64 * sizeof (uint8_t));

    mpeg2dec->chunk_buffer = (uint8_t *) mpeg2_malloc (BUFFER_SIZE + 4,
                                                       MPEG2_ALLOC_CHUNK);

    mpeg2dec->sequence.width = (unsigned)-1;
    mpeg2_reset (mpeg2dec, 1);

    return mpeg2dec;
}

void mpeg2_close (mpeg2dec_t * mpeg2dec)
{
    mpeg2_header_state_init (mpeg2dec);
    mpeg2_free (mpeg2dec->chunk_buffer);
    mpeg2_free (mpeg2dec);
}

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