mimic.c File Reference

#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "avcodec.h"
#include "bitstream.h"
#include "bytestream.h"
#include "dsputil.h"

Go to the source code of this file.

Data Structures
struct	MimicContext
Defines
#define	MIMIC_HEADER_SIZE   20
Functions
static av_cold int	mimic_decode_init (AVCodecContext *avctx)
static int	vlc_decode_block (MimicContext *ctx, int num_coeffs, int qscale)
static int	decode (MimicContext *ctx, int quality, int num_coeffs, int is_iframe)
static void	prepare_avpic (MimicContext *ctx, AVPicture *dst, AVPicture *src)
static int	mimic_decode_frame (AVCodecContext *avctx, void *data, int *data_size, const uint8_t *buf, int buf_size)
static av_cold int	mimic_decode_end (AVCodecContext *avctx)
Variables
static const uint32_t	huffcodes []
static const uint8_t	huffbits []
static const uint8_t	col_zag [64]
static const int8_t	vlcdec_lookup [9][64]
AVCodec	mimic_decoder

---

Define Documentation

#define MIMIC_HEADER_SIZE   20

Definition at line 31 of file mimic.c.

Referenced by mimic_decode_frame().

---

Function Documentation

static int decode	(	MimicContext *	ctx,
		int	quality,
		int	num_coeffs,
		int	is_iframe
	)			[static]

Definition at line 205 of file mimic.c.

References av_clip(), av_log(), AV_LOG_ERROR, MimicContext::avctx, MimicContext::cur_index, AVPicture::data, MimicContext::dsp, MimicContext::flipped_ptrs, MimicContext::gb, get_bits(), get_bits1(), DSPContext::idct_put, AVPicture::linesize, MimicContext::num_hblocks, MimicContext::num_vblocks, MimicContext::prev_index, DSPContext::put_pixels_tab, src, stride, and vlc_decode_block().

Referenced by ra288_decode_frame(), and show_formats().

{
    int y, x, plane;

    for(plane = 0; plane < 3; plane++) {
        const int is_chroma = !!plane;
        const int qscale = av_clip(10000-quality,is_chroma?1000:2000,10000)<<2;
        const int stride = ctx->flipped_ptrs[ctx->cur_index].linesize[plane];
        const uint8_t *src = ctx->flipped_ptrs[ctx->prev_index].data[plane];
        uint8_t       *dst = ctx->flipped_ptrs[ctx->cur_index ].data[plane];

        for(y = 0; y < ctx->num_vblocks[plane]; y++) {
            for(x = 0; x < ctx->num_hblocks[plane]; x++) {

                /* Check for a change condition in the current block.
                 * - iframes always change.
                 * - Luma plane changes on get_bits1 == 0
                 * - Chroma planes change on get_bits1 == 1 */
                if(is_iframe || get_bits1(&ctx->gb) == is_chroma) {

                    /* Luma planes may use a backreference from the 15 last
                     * frames preceding the previous. (get_bits1 == 1)
                     * Chroma planes don't use backreferences. */
                    if(is_chroma || is_iframe || !get_bits1(&ctx->gb)) {

                        if(!vlc_decode_block(ctx, num_coeffs, qscale))
                            return 0;
                        ctx->dsp.idct_put(dst, stride, ctx->dct_block);
                    } else {
                        unsigned int backref = get_bits(&ctx->gb, 4);
                        int index = (ctx->cur_index+backref)&15;
                        uint8_t *p = ctx->flipped_ptrs[index].data[0];

                        if(p) {
                            p += src -
                                ctx->flipped_ptrs[ctx->prev_index].data[plane];
                            ctx->dsp.put_pixels_tab[1][0](dst, p, stride, 8);
                        } else {
                            av_log(ctx->avctx, AV_LOG_ERROR,
                                     "No such backreference! Buggy sample.\n");
                        }
                    }
                } else {
                    ctx->dsp.put_pixels_tab[1][0](dst, src, stride, 8);
                }
                src += 8;
                dst += 8;
            }
            src += (stride - ctx->num_hblocks[plane])<<3;
            dst += (stride - ctx->num_hblocks[plane])<<3;
        }
    }

    return 1;
}

static av_cold int mimic_decode_end

(

AVCodecContext *

avctx

)

[static]

Definition at line 365 of file mimic.c.

References av_free(), MimicContext::buf_ptrs, free_vlc(), AVCodecContext::priv_data, AVCodecContext::release_buffer, MimicContext::swap_buf, and MimicContext::vlc.

{
    MimicContext *ctx = avctx->priv_data;
    int i;

    av_free(ctx->swap_buf);
    for(i = 0; i < 16; i++)
        if(ctx->buf_ptrs[i].data[0])
            avctx->release_buffer(avctx, &ctx->buf_ptrs[i]);
    free_vlc(&ctx->vlc);

    return 0;
}

static int mimic_decode_frame	(	AVCodecContext *	avctx,
		void *	data,
		int *	data_size,
		const uint8_t *	buf,
		int	buf_size
	)			[static]

Definition at line 276 of file mimic.c.

References av_log(), AV_LOG_ERROR, MimicContext::avctx, AVCodecContext::height, height, MIMIC_HEADER_SIZE, MimicContext::num_hblocks, MimicContext::num_vblocks, AVCodecContext::pix_fmt, PIX_FMT_YUV420P, AVCodecContext::priv_data, AVCodecContext::width, and width.

{
    MimicContext *ctx = avctx->priv_data;
    int is_pframe;
    int width, height;
    int quality, num_coeffs;
    int swap_buf_size = buf_size - MIMIC_HEADER_SIZE;

    if(buf_size < MIMIC_HEADER_SIZE) {
        av_log(avctx, AV_LOG_ERROR, "insufficient data\n");
        return -1;
    }

    buf       += 2; /* some constant (always 256) */
    quality    = bytestream_get_le16(&buf);
    width      = bytestream_get_le16(&buf);
    height     = bytestream_get_le16(&buf);
    buf       += 4; /* some constant */
    is_pframe  = bytestream_get_le32(&buf);
    num_coeffs = bytestream_get_byte(&buf);
    buf       += 3; /* some constant */

    if(!ctx->avctx) {
        int i;

        if(!(width == 160 && height == 120) &&
           !(width == 320 && height == 240)) {
            av_log(avctx, AV_LOG_ERROR, "invalid width/height!\n");
            return -1;
        }

        ctx->avctx     = avctx;
        avctx->width   = width;
        avctx->height  = height;
        avctx->pix_fmt = PIX_FMT_YUV420P;
        for(i = 0; i < 3; i++) {
            ctx->num_vblocks[i] = -((-height) >> (3 + !!i));
            ctx->num_hblocks[i] =     width   >> (3 + !!i) ;
        }
    } else if(width != ctx->avctx->width || height != ctx->avctx->height) {
        av_log(avctx, AV_LOG_ERROR, "resolution changing is not supported\n");
        return -1;
    }

    if(is_pframe && !ctx->buf_ptrs[ctx->prev_index].data[0]) {
        av_log(avctx, AV_LOG_ERROR, "decoding must start with keyframe\n");
        return -1;
    }

    ctx->buf_ptrs[ctx->cur_index].reference = 1;
    if(avctx->get_buffer(avctx, &ctx->buf_ptrs[ctx->cur_index])) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }

    prepare_avpic(ctx, &ctx->flipped_ptrs[ctx->cur_index],
                  (AVPicture*) &ctx->buf_ptrs[ctx->cur_index]);

    ctx->swap_buf = av_fast_realloc(ctx->swap_buf, &ctx->swap_buf_size,
                                 swap_buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
    if(!ctx->swap_buf)
        return AVERROR_NOMEM;

    ctx->dsp.bswap_buf((uint32_t*)ctx->swap_buf,
                        (const uint32_t*) buf,
                        swap_buf_size>>2);
    init_get_bits(&ctx->gb, ctx->swap_buf, swap_buf_size << 3);

    if(!decode(ctx, quality, num_coeffs, !is_pframe)) {
        avctx->release_buffer(avctx, &ctx->buf_ptrs[ctx->cur_index]);
        return -1;
    }

    ctx->buf_ptrs[ctx->cur_index].pict_type = is_pframe ? FF_P_TYPE:FF_I_TYPE;
    *(AVFrame*)data = ctx->buf_ptrs[ctx->cur_index];
    *data_size = sizeof(AVFrame);

    ctx->prev_index = ctx->cur_index;
    ctx->cur_index--;
    ctx->cur_index &= 15;

    /* Only release frames that aren't used for backreferences anymore */
    if(ctx->buf_ptrs[ctx->cur_index].data[0])
        avctx->release_buffer(avctx, &ctx->buf_ptrs[ctx->cur_index]);

    return buf_size;
}

static av_cold int mimic_decode_init

(

AVCodecContext *

avctx

)

[static]

Definition at line 106 of file mimic.c.

References av_log(), AV_LOG_ERROR, col_zag, MimicContext::cur_index, MimicContext::dsp, dsputil_init(), ff_init_scantable(), huffbits, huffcodes, DSPContext::idct_permutation, init_vlc, MimicContext::prev_index, AVCodecContext::priv_data, MimicContext::scantable, and MimicContext::vlc.

{
    MimicContext *ctx = avctx->priv_data;

    ctx->prev_index = 0;
    ctx->cur_index = 15;

    if(init_vlc(&ctx->vlc, 11, sizeof(huffbits)/sizeof(huffbits[0]),
                 huffbits, 1, 1, huffcodes, 4, 4, 0)) {
        av_log(avctx, AV_LOG_ERROR, "error initializing vlc table\n");
        return -1;
    }
    dsputil_init(&ctx->dsp, avctx);
    ff_init_scantable(ctx->dsp.idct_permutation, &ctx->scantable, col_zag);

    return 0;
}

static void prepare_avpic	(	MimicContext *	ctx,
		AVPicture *	dst,
		AVPicture *	src
	)			[static]

Flip the buffer upside-down and put it in the YVU order to match the way Mimic encodes frames.

Definition at line 266 of file mimic.c.

References MimicContext::avctx, AVPicture::data, AVCodecContext::height, AVPicture::linesize, and src.

{
    int i;
    dst->data[0] = src->data[0]+( ctx->avctx->height    -1)*src->linesize[0];
    dst->data[1] = src->data[2]+((ctx->avctx->height>>1)-1)*src->linesize[2];
    dst->data[2] = src->data[1]+((ctx->avctx->height>>1)-1)*src->linesize[1];
    for(i = 0; i < 3; i++)
        dst->linesize[i] = -src->linesize[i];
}

static int vlc_decode_block	(	MimicContext *	ctx,
		int	num_coeffs,
		int	qscale
	)			[static]

Definition at line 161 of file mimic.c.

References VLC::bits, MimicContext::gb, get_bits(), get_vlc2(), ScanTable::permutated, MimicContext::scantable, VLC::table, MimicContext::vlc, and vlcdec_lookup.

Referenced by decode().

{
    DCTELEM *block = ctx->dct_block;
    unsigned int pos;

    memset(block, 0, 64 * sizeof(DCTELEM));

    block[0] = get_bits(&ctx->gb, 8) << 3;

    for(pos = 1; pos < num_coeffs; pos++) {
        uint32_t vlc, num_bits;
        int value;
        int coeff;

        vlc = get_vlc2(&ctx->gb, ctx->vlc.table, ctx->vlc.bits, 3);
        if(!vlc) /* end-of-block code */
            return 1;
        if(vlc == -1)
            return 0;

        /* pos_add and num_bits are coded in the vlc code */
        pos +=     vlc&15; // pos_add
        num_bits = vlc>>4; // num_bits

        if(pos >= 64)
            return 0;

        value = get_bits(&ctx->gb, num_bits);

        /* FFmpeg's IDCT behaves somewhat different from the original code, so
         * a factor of 4 was added to the input */

        coeff = vlcdec_lookup[num_bits][value];
        if(pos<3)
            coeff <<= 4;
        else /* TODO Use >> 10 instead of / 1001 */
            coeff = (coeff * qscale) / 1001;

        block[ctx->scantable.permutated[pos]] = coeff;
    }

    return 1;
}

---

Variable Documentation

const uint8_t col_zag[64] [static]

Initial value:

 {
     0,  8,  1,  2,  9, 16, 24, 17,
    10,  3,  4, 11, 18, 25, 32, 40,
    33, 26, 19, 12,  5,  6, 13, 20,
    27, 34, 41, 48, 56, 49, 42, 35,
    28, 21, 14,  7, 15, 22, 29, 36,
    43, 50, 57, 58, 51, 44, 37, 30,
    23, 31, 38, 45, 52, 59, 39, 46,
    53, 60, 61, 54, 47, 55, 62, 63,
}

Definition at line 95 of file mimic.c.

Referenced by mimic_decode_init().

const uint8_t huffbits[] [static]

Initial value:

 {
     4,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
     0,  0,  0,  0,  2,  4,  5,  6,  7,  7,  7,  8,
     8, 10, 11, 11, 11, 11, 12, 12,  2,  6,  7,  8,
     9,  9, 12, 12, 13, 13, 13, 13, 14, 14, 14,  0,
     3,  6,  9, 14, 15, 15, 15, 15, 16, 16, 16, 16,
    17, 17, 17,  0,  4,  8,  9, 17, 18, 18, 18, 18,
    19, 19, 19, 19, 20, 20, 20,  0,  5, 10, 20, 21,
    21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23,  0,
     6, 10, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26,
    26, 26, 27,  0, 10, 27, 27, 27, 28, 28, 28, 28,
    29, 29, 29, 29, 30, 30, 30,
}

Definition at line 81 of file mimic.c.

Referenced by mimic_decode_init().

const uint32_t huffcodes[] [static]

Initial value:

 {
    0x0000000a, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x0000000b,
    0x0000001b, 0x00000038, 0x00000078, 0x00000079, 0x0000007a, 0x000000f9,
    0x000000fa, 0x000003fb, 0x000007f8, 0x000007f9, 0x000007fa, 0x000007fb,
    0x00000ff8, 0x00000ff9, 0x00000001, 0x00000039, 0x0000007b, 0x000000fb,
    0x000001f8, 0x000001f9, 0x00000ffa, 0x00000ffb, 0x00001ff8, 0x00001ff9,
    0x00001ffa, 0x00001ffb, 0x00003ff8, 0x00003ff9, 0x00003ffa, 0x00000000,
    0x00000004, 0x0000003a, 0x000001fa, 0x00003ffb, 0x00007ff8, 0x00007ff9,
    0x00007ffa, 0x00007ffb, 0x0000fff8, 0x0000fff9, 0x0000fffa, 0x0000fffb,
    0x0001fff8, 0x0001fff9, 0x0001fffa, 0x00000000, 0x0000000c, 0x000000f8,
    0x000001fb, 0x0001fffb, 0x0003fff8, 0x0003fff9, 0x0003fffa, 0x0003fffb,
    0x0007fff8, 0x0007fff9, 0x0007fffa, 0x0007fffb, 0x000ffff8, 0x000ffff9,
    0x000ffffa, 0x00000000, 0x0000001a, 0x000003f8, 0x000ffffb, 0x001ffff8,
    0x001ffff9, 0x001ffffa, 0x001ffffb, 0x003ffff8, 0x003ffff9, 0x003ffffa,
    0x003ffffb, 0x007ffff8, 0x007ffff9, 0x007ffffa, 0x007ffffb, 0x00000000,
    0x0000003b, 0x000003f9, 0x00fffff8, 0x00fffff9, 0x00fffffa, 0x00fffffb,
    0x01fffff8, 0x01fffff9, 0x01fffffa, 0x01fffffb, 0x03fffff8, 0x03fffff9,
    0x03fffffa, 0x03fffffb, 0x07fffff8, 0x00000000, 0x000003fa, 0x07fffff9,
    0x07fffffa, 0x07fffffb, 0x0ffffff8, 0x0ffffff9, 0x0ffffffa, 0x0ffffffb,
    0x1ffffff8, 0x1ffffff9, 0x1ffffffa, 0x1ffffffb, 0x3ffffff8, 0x3ffffff9,
    0x3ffffffa,
}

Definition at line 56 of file mimic.c.

Referenced by mimic_decode_init().

AVCodec mimic_decoder

Initial value:

 {
    "mimic",
    CODEC_TYPE_VIDEO,
    CODEC_ID_MIMIC,
    sizeof(MimicContext),
    mimic_decode_init,
    NULL,
    mimic_decode_end,
    mimic_decode_frame,
    CODEC_CAP_DR1,
    .long_name = NULL_IF_CONFIG_SMALL("Mimic"),
}

Definition at line 379 of file mimic.c.

const int8_t vlcdec_lookup[9][64] [static]

Definition at line 124 of file mimic.c.

Referenced by vlc_decode_block().

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