FFmpeg coverage

GCC Code Coverage Report

Directory:	../../../ffmpeg/		Exec	Total	Coverage
File:	src/libavcodec/h261dec.c	Lines:	268	337	79.5 %
Date:	2021-01-21 21:11:50	Branches:	123	186	66.1 %


/*
 * H.261 decoder
 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
 * Copyright (c) 2004 Maarten Daniels
 *
 * 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
 * H.261 decoder.
 */

#include "libavutil/avassert.h"
#include "avcodec.h"
#include "mpeg_er.h"
#include "mpegutils.h"
#include "mpegvideo.h"
#include "h263.h"
#include "h261.h"
#include "internal.h"

#define H261_MBA_VLC_BITS 9
#define H261_MTYPE_VLC_BITS 6
#define H261_MV_VLC_BITS 7
#define H261_CBP_VLC_BITS 9
#define TCOEFF_VLC_BITS 9
#define MBA_STUFFING 33
#define MBA_STARTCODE 34

static VLC h261_mba_vlc;
static VLC h261_mtype_vlc;
static VLC h261_mv_vlc;
static VLC h261_cbp_vlc;

static av_cold void h261_decode_init_vlc(H261Context *h)
{
    static int done = 0;

    if (!done) {
        done = 1;
        INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
                        ff_h261_mba_bits, 1, 1,
                        ff_h261_mba_code, 1, 1, 662);
        INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
                        ff_h261_mtype_bits, 1, 1,
                        ff_h261_mtype_code, 1, 1, 80);
        INIT_VLC_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
                        &ff_h261_mv_tab[0][1], 2, 1,
                        &ff_h261_mv_tab[0][0], 2, 1, 144);
        INIT_VLC_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
                        &ff_h261_cbp_tab[0][1], 2, 1,
                        &ff_h261_cbp_tab[0][0], 2, 1, 512);
        INIT_VLC_RL(ff_h261_rl_tcoeff, 552);
    }
}

static av_cold int h261_decode_init(AVCodecContext *avctx)
{
    H261Context *h          = avctx->priv_data;
    MpegEncContext *const s = &h->s;

    // set defaults
    ff_mpv_decode_init(s, avctx);

    s->out_format  = FMT_H261;
    s->low_delay   = 1;
    avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    ff_h261_common_init();
    h261_decode_init_vlc(h);

    h->gob_start_code_skipped = 0;

    return 0;
}

/**
 * Decode the group of blocks header or slice header.
 * @return <0 if an error occurred
 */
static int h261_decode_gob_header(H261Context *h)
{
    unsigned int val;
    MpegEncContext *const s = &h->s;

    if (!h->gob_start_code_skipped) {
        /* Check for GOB Start Code */
        val = show_bits(&s->gb, 15);
        if (val)
            return -1;

        /* We have a GBSC */
        skip_bits(&s->gb, 16);
    }

    h->gob_start_code_skipped = 0;

    h->gob_number = get_bits(&s->gb, 4); /* GN */
    s->qscale     = get_bits(&s->gb, 5); /* GQUANT */

    /* Check if gob_number is valid */
    if (s->mb_height == 18) { // CIF
        if ((h->gob_number <= 0) || (h->gob_number > 12))
            return -1;
    } else { // QCIF
        if ((h->gob_number != 1) && (h->gob_number != 3) &&
            (h->gob_number != 5))
            return -1;
    }

    /* GEI */
    if (skip_1stop_8data_bits(&s->gb) < 0)
        return AVERROR_INVALIDDATA;

    if (s->qscale == 0) {
        av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n");
        if (s->avctx->err_recognition & (AV_EF_BITSTREAM | AV_EF_COMPLIANT))
            return -1;
    }

    /* For the first transmitted macroblock in a GOB, MBA is the absolute
     * address. For subsequent macroblocks, MBA is the difference between
     * the absolute addresses of the macroblock and the last transmitted
     * macroblock. */
    h->current_mba = 0;
    h->mba_diff    = 0;

    return 0;
}

/**
 * Decode the group of blocks / video packet header.
 * @return <0 if no resync found
 */
static int h261_resync(H261Context *h)
{
    MpegEncContext *const s = &h->s;
    int left, ret;

    if (h->gob_start_code_skipped) {
        ret = h261_decode_gob_header(h);
        if (ret >= 0)
            return 0;
    } else {
        if (show_bits(&s->gb, 15) == 0) {
            ret = h261_decode_gob_header(h);
            if (ret >= 0)
                return 0;
        }
        // OK, it is not where it is supposed to be ...
        s->gb = s->last_resync_gb;
        align_get_bits(&s->gb);
        left = get_bits_left(&s->gb);

        for (; left > 15 + 1 + 4 + 5; left -= 8) {
            if (show_bits(&s->gb, 15) == 0) {
                GetBitContext bak = s->gb;

                ret = h261_decode_gob_header(h);
                if (ret >= 0)
                    return 0;

                s->gb = bak;
            }
            skip_bits(&s->gb, 8);
        }
    }

    return -1;
}

/**
 * Decode skipped macroblocks.
 * @return 0
 */
static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2)
{
    MpegEncContext *const s = &h->s;
    int i;

    s->mb_intra = 0;

    for (i = mba1; i < mba2; i++) {
        int j, xy;

        s->mb_x = ((h->gob_number - 1) % 2) * 11 + i % 11;
        s->mb_y = ((h->gob_number - 1) / 2) * 3 + i / 11;
        xy      = s->mb_x + s->mb_y * s->mb_stride;
        ff_init_block_index(s);
        ff_update_block_index(s);

        for (j = 0; j < 6; j++)
            s->block_last_index[j] = -1;

        s->mv_dir                      = MV_DIR_FORWARD;
        s->mv_type                     = MV_TYPE_16X16;
        s->current_picture.mb_type[xy] = MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
        s->mv[0][0][0]                 = 0;
        s->mv[0][0][1]                 = 0;
        s->mb_skipped                  = 1;
        h->mtype                      &= ~MB_TYPE_H261_FIL;

        if (s->current_picture.motion_val[0]) {
            int b_stride = 2*s->mb_width + 1;
            int b_xy     = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
            s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
            s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
        }

        ff_mpv_reconstruct_mb(s, s->block);
    }

    return 0;
}

static const int mvmap[17] = {
    0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16
};

static int decode_mv_component(GetBitContext *gb, int v)
{
    int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);

    /* check if mv_diff is valid */
    if (mv_diff < 0)
        return v;

    mv_diff = mvmap[mv_diff];

    if (mv_diff && !get_bits1(gb))
        mv_diff = -mv_diff;

    v += mv_diff;
    if (v <= -16)
        v += 32;
    else if (v >= 16)
        v -= 32;

    return v;
}

/**
 * Decode a macroblock.
 * @return <0 if an error occurred
 */
static int h261_decode_block(H261Context *h, int16_t *block, int n, int coded)
{
    MpegEncContext *const s = &h->s;
    int level, i, j, run;
    RLTable *rl = &ff_h261_rl_tcoeff;
    const uint8_t *scan_table;

    /* For the variable length encoding there are two code tables, one being
     * used for the first transmitted LEVEL in INTER, INTER + MC and
     * INTER + MC + FIL blocks, the second for all other LEVELs except the
     * first one in INTRA blocks which is fixed length coded with 8 bits.
     * NOTE: The two code tables only differ in one VLC so we handle that
     * manually. */
    scan_table = s->intra_scantable.permutated;
    if (s->mb_intra) {
        /* DC coef */
        level = get_bits(&s->gb, 8);
        // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
        if ((level & 0x7F) == 0) {
            av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n",
                   level, s->mb_x, s->mb_y);
            return -1;
        }
        /* The code 1000 0000 is not used, the reconstruction level of 1024
         * being coded as 1111 1111. */
        if (level == 255)
            level = 128;
        block[0] = level;
        i        = 1;
    } else if (coded) {
        // Run  Level   Code
        // EOB          Not possible for first level when cbp is available (that's why the table is different)
        // 0    1       1s
        // *    *       0*
        int check = show_bits(&s->gb, 2);
        i = 0;
        if (check & 0x2) {
            skip_bits(&s->gb, 2);
            block[0] = (check & 0x1) ? -1 : 1;
            i        = 1;
        }
    } else {
        i = 0;
    }
    if (!coded) {
        s->block_last_index[n] = i - 1;
        return 0;
    }
    {
    OPEN_READER(re, &s->gb);
    i--; // offset by -1 to allow direct indexing of scan_table
    for (;;) {
        UPDATE_CACHE(re, &s->gb);
        GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
        if (run == 66) {
            if (level) {
                CLOSE_READER(re, &s->gb);
                av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n",
                       s->mb_x, s->mb_y);
                return -1;
            }
            /* escape */
            /* The remaining combinations of (run, level) are encoded with a
             * 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits
             * level. */
            run   = SHOW_UBITS(re, &s->gb, 6) + 1;
            SKIP_CACHE(re, &s->gb, 6);
            level = SHOW_SBITS(re, &s->gb, 8);
            SKIP_COUNTER(re, &s->gb, 6 + 8);
        } else if (level == 0) {
            break;
        } else {
            if (SHOW_UBITS(re, &s->gb, 1))
                level = -level;
            SKIP_COUNTER(re, &s->gb, 1);
        }
        i += run;
        if (i >= 64) {
            CLOSE_READER(re, &s->gb);
            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n",
                   s->mb_x, s->mb_y);
            return -1;
        }
        j        = scan_table[i];
        block[j] = level;
    }
    CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
    return 0;
}

static int h261_decode_mb(H261Context *h)
{
    MpegEncContext *const s = &h->s;
    int i, cbp, xy;

    cbp = 63;
    // Read mba
    do {
        h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table,
                               H261_MBA_VLC_BITS, 2);

        /* Check for slice end */
        /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
        if (h->mba_diff == MBA_STARTCODE) { // start code
            h->gob_start_code_skipped = 1;
            return SLICE_END;
        }
    } while (h->mba_diff == MBA_STUFFING); // stuffing

    if (h->mba_diff < 0) {
        if (get_bits_left(&s->gb) <= 7)
            return SLICE_END;

        av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
        return SLICE_ERROR;
    }

    h->mba_diff    += 1;
    h->current_mba += h->mba_diff;

    if (h->current_mba > MBA_STUFFING)
        return SLICE_ERROR;

    s->mb_x = ((h->gob_number - 1) % 2) * 11 + ((h->current_mba - 1) % 11);
    s->mb_y = ((h->gob_number - 1) / 2) * 3 + ((h->current_mba - 1) / 11);
    xy      = s->mb_x + s->mb_y * s->mb_stride;
    ff_init_block_index(s);
    ff_update_block_index(s);

    // Read mtype
    h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
    if (h->mtype < 0) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index %d\n",
               h->mtype);
        return SLICE_ERROR;
    }
    av_assert0(h->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map));
    h->mtype = ff_h261_mtype_map[h->mtype];

    // Read mquant
    if (IS_QUANT(h->mtype))
        ff_set_qscale(s, get_bits(&s->gb, 5));

    s->mb_intra = IS_INTRA4x4(h->mtype);

    // Read mv
    if (IS_16X16(h->mtype)) {
        /* Motion vector data is included for all MC macroblocks. MVD is
         * obtained from the macroblock vector by subtracting the vector
         * of the preceding macroblock. For this calculation the vector
         * of the preceding macroblock is regarded as zero in the
         * following three situations:
         * 1) evaluating MVD for macroblocks 1, 12 and 23;
         * 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
         * 3) MTYPE of the previous macroblock was not MC. */
        if ((h->current_mba ==  1) || (h->current_mba == 12) ||
            (h->current_mba == 23) || (h->mba_diff != 1)) {
            h->current_mv_x = 0;
            h->current_mv_y = 0;
        }

        h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x);
        h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y);
    } else {
        h->current_mv_x = 0;
        h->current_mv_y = 0;
    }

    // Read cbp
    if (HAS_CBP(h->mtype))
        cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 1) + 1;

    if (s->mb_intra) {
        s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
        goto intra;
    }

    //set motion vectors
    s->mv_dir                      = MV_DIR_FORWARD;
    s->mv_type                     = MV_TYPE_16X16;
    s->current_picture.mb_type[xy] = MB_TYPE_16x16 | MB_TYPE_L0;
    s->mv[0][0][0]                 = h->current_mv_x * 2; // gets divided by 2 in motion compensation
    s->mv[0][0][1]                 = h->current_mv_y * 2;

    if (s->current_picture.motion_val[0]) {
        int b_stride = 2*s->mb_width + 1;
        int b_xy     = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
        s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
        s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
    }

intra:
    /* decode each block */
    if (s->mb_intra || HAS_CBP(h->mtype)) {
        s->bdsp.clear_blocks(s->block[0]);
        for (i = 0; i < 6; i++) {
            if (h261_decode_block(h, s->block[i], i, cbp & 32) < 0)
                return SLICE_ERROR;
            cbp += cbp;
        }
    } else {
        for (i = 0; i < 6; i++)
            s->block_last_index[i] = -1;
    }

    ff_mpv_reconstruct_mb(s, s->block);

    return SLICE_OK;
}

/**
 * Decode the H.261 picture header.
 * @return <0 if no startcode found
 */
static int h261_decode_picture_header(H261Context *h)
{
    MpegEncContext *const s = &h->s;
    int format, i;
    uint32_t startcode = 0;

    for (i = get_bits_left(&s->gb); i > 24; i -= 1) {
        startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;

        if (startcode == 0x10)
            break;
    }

    if (startcode != 0x10) {
        av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
        return -1;
    }

    /* temporal reference */
    i = get_bits(&s->gb, 5); /* picture timestamp */
    if (i < (s->picture_number & 31))
        i += 32;
    s->picture_number = (s->picture_number & ~31) + i;

    s->avctx->framerate = (AVRational) { 30000, 1001 };

    /* PTYPE starts here */
    skip_bits1(&s->gb); /* split screen off */
    skip_bits1(&s->gb); /* camera  off */
    skip_bits1(&s->gb); /* freeze picture release off */

    format = get_bits1(&s->gb);

    // only 2 formats possible
    if (format == 0) { // QCIF
        s->width     = 176;
        s->height    = 144;
        s->mb_width  = 11;
        s->mb_height = 9;
    } else { // CIF
        s->width     = 352;
        s->height    = 288;
        s->mb_width  = 22;
        s->mb_height = 18;
    }

    s->mb_num = s->mb_width * s->mb_height;

    skip_bits1(&s->gb); /* still image mode off */
    skip_bits1(&s->gb); /* Reserved */

    /* PEI */
    if (skip_1stop_8data_bits(&s->gb) < 0)
        return AVERROR_INVALIDDATA;

    /* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first
     * frame, the codec crashes if it does not contain all I-blocks
     * (e.g. when a packet is lost). */
    s->pict_type = AV_PICTURE_TYPE_P;

    h->gob_number = 0;
    return 0;
}

static int h261_decode_gob(H261Context *h)
{
    MpegEncContext *const s = &h->s;

    ff_set_qscale(s, s->qscale);

    /* decode mb's */
    while (h->current_mba <= MBA_STUFFING) {
        int ret;
        /* DCT & quantize */
        ret = h261_decode_mb(h);
        if (ret < 0) {
            if (ret == SLICE_END) {
                h261_decode_mb_skipped(h, h->current_mba, 33);
                return 0;
            }
            av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n",
                   s->mb_x + s->mb_y * s->mb_stride);
            return -1;
        }

        h261_decode_mb_skipped(h,
                               h->current_mba - h->mba_diff,
                               h->current_mba - 1);
    }

    return -1;
}

/**
 * returns the number of bytes consumed for building the current frame
 */
static int get_consumed_bytes(MpegEncContext *s, int buf_size)
{
    int pos = get_bits_count(&s->gb) >> 3;
    if (pos == 0)
        pos = 1;      // avoid infinite loops (i doubt that is needed but ...)
    if (pos + 10 > buf_size)
        pos = buf_size;               // oops ;)

    return pos;
}

static int h261_decode_frame(AVCodecContext *avctx, void *data,
                             int *got_frame, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    H261Context *h     = avctx->priv_data;
    MpegEncContext *s  = &h->s;
    int ret;
    AVFrame *pict = data;

    ff_dlog(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size);
    ff_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);

    h->gob_start_code_skipped = 0;

retry:
    init_get_bits(&s->gb, buf, buf_size * 8);

    if (!s->context_initialized)
        // we need the IDCT permutation for reading a custom matrix
        ff_mpv_idct_init(s);

    ret = h261_decode_picture_header(h);

    /* skip if the header was thrashed */
    if (ret < 0) {
        av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
        return -1;
    }

    if (s->width != avctx->coded_width || s->height != avctx->coded_height) {
        ParseContext pc = s->parse_context; // FIXME move this demuxing hack to libavformat
        s->parse_context.buffer = 0;
        ff_mpv_common_end(s);
        s->parse_context = pc;
    }

    if (!s->context_initialized) {
        if ((ret = ff_mpv_common_init(s)) < 0)
            return ret;

        ret = ff_set_dimensions(avctx, s->width, s->height);
        if (ret < 0)
            return ret;

        goto retry;
    }

    // for skipping the frame
    s->current_picture.f->pict_type = s->pict_type;
    s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;

    if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) ||
        (avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) ||
         avctx->skip_frame >= AVDISCARD_ALL)
        return get_consumed_bytes(s, buf_size);

    if (ff_mpv_frame_start(s, avctx) < 0)
        return -1;

    ff_mpeg_er_frame_start(s);

    /* decode each macroblock */
    s->mb_x = 0;
    s->mb_y = 0;

    while (h->gob_number < (s->mb_height == 18 ? 12 : 5)) {
        if (h261_resync(h) < 0)
            break;
        h261_decode_gob(h);
    }
    ff_mpv_frame_end(s);

    av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type);
    av_assert0(s->current_picture.f->pict_type == s->pict_type);

    if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0)
        return ret;
    ff_print_debug_info(s, s->current_picture_ptr, pict);

    *got_frame = 1;

    return get_consumed_bytes(s, buf_size);
}

static av_cold int h261_decode_end(AVCodecContext *avctx)
{
    H261Context *h    = avctx->priv_data;
    MpegEncContext *s = &h->s;

    ff_mpv_common_end(s);
    return 0;
}

AVCodec ff_h261_decoder = {
    .name           = "h261",
    .long_name      = NULL_IF_CONFIG_SMALL("H.261"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_H261,
    .priv_data_size = sizeof(H261Context),
    .init           = h261_decode_init,
    .close          = h261_decode_end,
    .decode         = h261_decode_frame,
    .capabilities   = AV_CODEC_CAP_DR1,
    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
    .max_lowres     = 3,
};


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1			/*
2			* H.261 decoder
3			* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4			* Copyright (c) 2004 Maarten Daniels
5			*
6			* This file is part of FFmpeg.
7			*
8			* FFmpeg is free software; you can redistribute it and/or
9			* modify it under the terms of the GNU Lesser General Public
10			* License as published by the Free Software Foundation; either
11			* version 2.1 of the License, or (at your option) any later version.
12			*
13			* FFmpeg is distributed in the hope that it will be useful,
14			* but WITHOUT ANY WARRANTY; without even the implied warranty of
15			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16			* Lesser General Public License for more details.
17			*
18			* You should have received a copy of the GNU Lesser General Public
19			* License along with FFmpeg; if not, write to the Free Software
20			* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21			*/
22
23			/**
24			* @file
25			* H.261 decoder.
26			*/
27
28			#include "libavutil/avassert.h"
29			#include "avcodec.h"
30			#include "mpeg_er.h"
31			#include "mpegutils.h"
32			#include "mpegvideo.h"
33			#include "h263.h"
34			#include "h261.h"
35			#include "internal.h"
36
37			#define H261_MBA_VLC_BITS 9
38			#define H261_MTYPE_VLC_BITS 6
39			#define H261_MV_VLC_BITS 7
40			#define H261_CBP_VLC_BITS 9
41			#define TCOEFF_VLC_BITS 9
42			#define MBA_STUFFING 33
43			#define MBA_STARTCODE 34
44
45			static VLC h261_mba_vlc;
46			static VLC h261_mtype_vlc;
47			static VLC h261_mv_vlc;
48			static VLC h261_cbp_vlc;
49
50		13	static av_cold void h261_decode_init_vlc(H261Context *h)
51			{
52			static int done = 0;
53
54	✓✓	13	if (!done) {
55		7	done = 1;
56		7	INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
57			ff_h261_mba_bits, 1, 1,
58			ff_h261_mba_code, 1, 1, 662);
59		7	INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
60			ff_h261_mtype_bits, 1, 1,
61			ff_h261_mtype_code, 1, 1, 80);
62		7	INIT_VLC_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
63			&ff_h261_mv_tab[0][1], 2, 1,
64			&ff_h261_mv_tab[0][0], 2, 1, 144);
65		7	INIT_VLC_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
66			&ff_h261_cbp_tab[0][1], 2, 1,
67			&ff_h261_cbp_tab[0][0], 2, 1, 512);
68	✓✗✓✓	231	INIT_VLC_RL(ff_h261_rl_tcoeff, 552);
69			}
70		13	}
71
72		13	static av_cold int h261_decode_init(AVCodecContext *avctx)
73			{
74		13	H261Context *h = avctx->priv_data;
75		13	MpegEncContext *const s = &h->s;
76
77			// set defaults
78		13	ff_mpv_decode_init(s, avctx);
79
80		13	s->out_format = FMT_H261;
81		13	s->low_delay = 1;
82		13	avctx->pix_fmt = AV_PIX_FMT_YUV420P;
83
84		13	ff_h261_common_init();
85		13	h261_decode_init_vlc(h);
86
87		13	h->gob_start_code_skipped = 0;
88
89		13	return 0;
90			}
91
92			/**
93			* Decode the group of blocks header or slice header.
94			* @return <0 if an error occurred
95			*/
96		3600	static int h261_decode_gob_header(H261Context *h)
97			{
98			unsigned int val;
99		3600	MpegEncContext *const s = &h->s;
100
101	✓✓	3600	if (!h->gob_start_code_skipped) {
102			/* Check for GOB Start Code */
103		300	val = show_bits(&s->gb, 15);
104	✗✓	300	if (val)
105			return -1;
106
107			/* We have a GBSC */
108		300	skip_bits(&s->gb, 16);
109			}
110
111		3600	h->gob_start_code_skipped = 0;
112
113		3600	h->gob_number = get_bits(&s->gb, 4); /* GN */
114		3600	s->qscale = get_bits(&s->gb, 5); /* GQUANT */
115
116			/* Check if gob_number is valid */
117	✓✗	3600	if (s->mb_height == 18) { // CIF
118	✓✗✗✓	3600	if ((h->gob_number <= 0) \|\| (h->gob_number > 12))
119			return -1;
120			} else { // QCIF
121			if ((h->gob_number != 1) && (h->gob_number != 3) &&
122			(h->gob_number != 5))
123			return -1;
124			}
125
126			/* GEI */
127	✗✓	3600	if (skip_1stop_8data_bits(&s->gb) < 0)
128			return AVERROR_INVALIDDATA;
129
130	✗✓	3600	if (s->qscale == 0) {
131			av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n");
132			if (s->avctx->err_recognition & (AV_EF_BITSTREAM \| AV_EF_COMPLIANT))
133			return -1;
134			}
135
136			/* For the first transmitted macroblock in a GOB, MBA is the absolute
137			* address. For subsequent macroblocks, MBA is the difference between
138			* the absolute addresses of the macroblock and the last transmitted
139			* macroblock. */
140		3600	h->current_mba = 0;
141		3600	h->mba_diff = 0;
142
143		3600	return 0;
144			}
145
146			/**
147			* Decode the group of blocks / video packet header.
148			* @return <0 if no resync found
149			*/
150		3600	static int h261_resync(H261Context *h)
151			{
152		3600	MpegEncContext *const s = &h->s;
153			int left, ret;
154
155	✓✓	3600	if (h->gob_start_code_skipped) {
156		3300	ret = h261_decode_gob_header(h);
157	✓✗	3300	if (ret >= 0)
158		3300	return 0;
159			} else {
160	✓✗	300	if (show_bits(&s->gb, 15) == 0) {
161		300	ret = h261_decode_gob_header(h);
162	✓✗	300	if (ret >= 0)
163		300	return 0;
164			}
165			// OK, it is not where it is supposed to be ...
166			s->gb = s->last_resync_gb;
167			align_get_bits(&s->gb);
168			left = get_bits_left(&s->gb);
169
170			for (; left > 15 + 1 + 4 + 5; left -= 8) {
171			if (show_bits(&s->gb, 15) == 0) {
172			GetBitContext bak = s->gb;
173
174			ret = h261_decode_gob_header(h);
175			if (ret >= 0)
176			return 0;
177
178			s->gb = bak;
179			}
180			skip_bits(&s->gb, 8);
181			}
182			}
183
184			return -1;
185			}
186
187			/**
188			* Decode skipped macroblocks.
189			* @return 0
190			*/
191		121514	static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2)
192			{
193		121514	MpegEncContext *const s = &h->s;
194			int i;
195
196		121514	s->mb_intra = 0;
197
198	✓✓	122400	for (i = mba1; i < mba2; i++) {
199			int j, xy;
200
201		886	s->mb_x = ((h->gob_number - 1) % 2) * 11 + i % 11;
202		886	s->mb_y = ((h->gob_number - 1) / 2) * 3 + i / 11;
203		886	xy = s->mb_x + s->mb_y * s->mb_stride;
204		886	ff_init_block_index(s);
205		886	ff_update_block_index(s);
206
207	✓✓	6202	for (j = 0; j < 6; j++)
208		5316	s->block_last_index[j] = -1;
209
210		886	s->mv_dir = MV_DIR_FORWARD;
211		886	s->mv_type = MV_TYPE_16X16;
212		886	s->current_picture.mb_type[xy] = MB_TYPE_SKIP \| MB_TYPE_16x16 \| MB_TYPE_L0;
213		886	s->mv[0][0][0] = 0;
214		886	s->mv[0][0][1] = 0;
215		886	s->mb_skipped = 1;
216		886	h->mtype &= ~MB_TYPE_H261_FIL;
217
218	✗✓	886	if (s->current_picture.motion_val[0]) {
219			int b_stride = 2*s->mb_width + 1;
220			int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
221			s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
222			s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
223			}
224
225		886	ff_mpv_reconstruct_mb(s, s->block);
226			}
227
228		121514	return 0;
229			}
230
231			static const int mvmap[17] = {
232			0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16
233			};
234
235		193928	static int decode_mv_component(GetBitContext *gb, int v)
236			{
237		193928	int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
238
239			/* check if mv_diff is valid */
240	✗✓	193928	if (mv_diff < 0)
241			return v;
242
243		193928	mv_diff = mvmap[mv_diff];
244
245	✓✓✓✓	193928	if (mv_diff && !get_bits1(gb))
246		37209	mv_diff = -mv_diff;
247
248		193928	v += mv_diff;
249	✓✓	193928	if (v <= -16)
250		36	v += 32;
251	✓✓	193892	else if (v >= 16)
252		30	v -= 32;
253
254		193928	return v;
255			}
256
257			/**
258			* Decode a macroblock.
259			* @return <0 if an error occurred
260			*/
261		590082	static int h261_decode_block(H261Context h, int16_t block, int n, int coded)
262			{
263		590082	MpegEncContext *const s = &h->s;
264			int level, i, j, run;
265		590082	RLTable *rl = &ff_h261_rl_tcoeff;
266			const uint8_t *scan_table;
267
268			/* For the variable length encoding there are two code tables, one being
269			* used for the first transmitted LEVEL in INTER, INTER + MC and
270			* INTER + MC + FIL blocks, the second for all other LEVELs except the
271			* first one in INTRA blocks which is fixed length coded with 8 bits.
272			* NOTE: The two code tables only differ in one VLC so we handle that
273			* manually. */
274		590082	scan_table = s->intra_scantable.permutated;
275	✓✓	590082	if (s->mb_intra) {
276			/* DC coef */
277		106194	level = get_bits(&s->gb, 8);
278			// 0 (00000000b) and -128 (10000000b) are FORBIDDEN
279	✗✓	106194	if ((level & 0x7F) == 0) {
280			av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n",
281			level, s->mb_x, s->mb_y);
282			return -1;
283			}
284			/* The code 1000 0000 is not used, the reconstruction level of 1024
285			* being coded as 1111 1111. */
286	✓✓	106194	if (level == 255)
287		1211	level = 128;
288		106194	block[0] = level;
289		106194	i = 1;
290	✓✓	483888	} else if (coded) {
291			// Run Level Code
292			// EOB Not possible for first level when cbp is available (that's why the table is different)
293			// 0 1 1s
294			// * * 0*
295		242540	int check = show_bits(&s->gb, 2);
296		242540	i = 0;
297	✓✓	242540	if (check & 0x2) {
298		81615	skip_bits(&s->gb, 2);
299	✓✓	81615	block[0] = (check & 0x1) ? -1 : 1;
300		81615	i = 1;
301			}
302			} else {
303		241348	i = 0;
304			}
305	✓✓	590082	if (!coded) {
306		241348	s->block_last_index[n] = i - 1;
307		241348	return 0;
308			}
309			{
310		348734	OPEN_READER(re, &s->gb);
311		348734	i--; // offset by -1 to allow direct indexing of scan_table
312			for (;;) {
313		2586037	UPDATE_CACHE(re, &s->gb);
314	✓✓	2586037	GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
315	✓✓	2586037	if (run == 66) {
316	✗✓	65180	if (level) {
317			CLOSE_READER(re, &s->gb);
318			av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n",
319			s->mb_x, s->mb_y);
320			return -1;
321			}
322			/* escape */
323			/* The remaining combinations of (run, level) are encoded with a
324			* 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits
325			* level. */
326		65180	run = SHOW_UBITS(re, &s->gb, 6) + 1;
327		65180	SKIP_CACHE(re, &s->gb, 6);
328		65180	level = SHOW_SBITS(re, &s->gb, 8);
329		65180	SKIP_COUNTER(re, &s->gb, 6 + 8);
330	✓✓	2520857	} else if (level == 0) {
331		348734	break;
332			} else {
333	✓✓	2172123	if (SHOW_UBITS(re, &s->gb, 1))
334		1087153	level = -level;
335		2172123	SKIP_COUNTER(re, &s->gb, 1);
336			}
337		2237303	i += run;
338	✗✓	2237303	if (i >= 64) {
339			CLOSE_READER(re, &s->gb);
340			av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n",
341			s->mb_x, s->mb_y);
342			return -1;
343			}
344		2237303	j = scan_table[i];
345		2237303	block[j] = level;
346			}
347		348734	CLOSE_READER(re, &s->gb);
348			}
349		348734	s->block_last_index[n] = i;
350		348734	return 0;
351			}
352
353		121514	static int h261_decode_mb(H261Context *h)
354			{
355		121514	MpegEncContext *const s = &h->s;
356			int i, cbp, xy;
357
358		121514	cbp = 63;
359			// Read mba
360			do {
361		121514	h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table,
362			H261_MBA_VLC_BITS, 2);
363
364			/* Check for slice end */
365			/* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
366	✓✓	121514	if (h->mba_diff == MBA_STARTCODE) { // start code
367		3300	h->gob_start_code_skipped = 1;
368		3300	return SLICE_END;
369			}
370	✗✓	118214	} while (h->mba_diff == MBA_STUFFING); // stuffing
371
372	✓✓	118214	if (h->mba_diff < 0) {
373	✓✗	300	if (get_bits_left(&s->gb) <= 7)
374		300	return SLICE_END;
375
376			av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
377			return SLICE_ERROR;
378			}
379
380		117914	h->mba_diff += 1;
381		117914	h->current_mba += h->mba_diff;
382
383	✗✓	117914	if (h->current_mba > MBA_STUFFING)
384			return SLICE_ERROR;
385
386		117914	s->mb_x = ((h->gob_number - 1) % 2) * 11 + ((h->current_mba - 1) % 11);
387		117914	s->mb_y = ((h->gob_number - 1) / 2) * 3 + ((h->current_mba - 1) / 11);
388		117914	xy = s->mb_x + s->mb_y * s->mb_stride;
389		117914	ff_init_block_index(s);
390		117914	ff_update_block_index(s);
391
392			// Read mtype
393		117914	h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
394	✗✓	117914	if (h->mtype < 0) {
395			av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index %d\n",
396			h->mtype);
397			return SLICE_ERROR;
398			}
399	✗✓	117914	av_assert0(h->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map));
400		117914	h->mtype = ff_h261_mtype_map[h->mtype];
401
402			// Read mquant
403	✗✓	117914	if (IS_QUANT(h->mtype))
404			ff_set_qscale(s, get_bits(&s->gb, 5));
405
406		117914	s->mb_intra = IS_INTRA4x4(h->mtype);
407
408			// Read mv
409	✓✓	117914	if (IS_16X16(h->mtype)) {
410			/* Motion vector data is included for all MC macroblocks. MVD is
411			* obtained from the macroblock vector by subtracting the vector
412			* of the preceding macroblock. For this calculation the vector
413			* of the preceding macroblock is regarded as zero in the
414			* following three situations:
415			* 1) evaluating MVD for macroblocks 1, 12 and 23;
416			* 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
417			* 3) MTYPE of the previous macroblock was not MC. */
418	✓✓✓✓	96964	if ((h->current_mba == 1) \|\| (h->current_mba == 12) \|\|
419	✓✓✓✓	91569	(h->current_mba == 23) \|\| (h->mba_diff != 1)) {
420		8682	h->current_mv_x = 0;
421		8682	h->current_mv_y = 0;
422			}
423
424		96964	h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x);
425		96964	h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y);
426			} else {
427		20950	h->current_mv_x = 0;
428		20950	h->current_mv_y = 0;
429			}
430
431			// Read cbp
432	✓✓	117914	if (HAS_CBP(h->mtype))
433		80648	cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 1) + 1;
434
435	✓✓	117914	if (s->mb_intra) {
436		17699	s->current_picture.mb_type[xy] = MB_TYPE_INTRA;
437		17699	goto intra;
438			}
439
440			//set motion vectors
441		100215	s->mv_dir = MV_DIR_FORWARD;
442		100215	s->mv_type = MV_TYPE_16X16;
443		100215	s->current_picture.mb_type[xy] = MB_TYPE_16x16 \| MB_TYPE_L0;
444		100215	s->mv[0][0][0] = h->current_mv_x * 2; // gets divided by 2 in motion compensation
445		100215	s->mv[0][0][1] = h->current_mv_y * 2;
446
447	✓✗	100215	if (s->current_picture.motion_val[0]) {
448			int b_stride = 2*s->mb_width + 1;
449			int b_xy = 2 * s->mb_x + (2 * s->mb_y) * b_stride;
450			s->current_picture.motion_val[0][b_xy][0] = s->mv[0][0][0];
451			s->current_picture.motion_val[0][b_xy][1] = s->mv[0][0][1];
452			}
453
454		100215	intra:
455			/* decode each block */
456	✓✓✓✓	117914	if (s->mb_intra \|\| HAS_CBP(h->mtype)) {
457		98347	s->bdsp.clear_blocks(s->block[0]);
458	✓✓	688429	for (i = 0; i < 6; i++) {
459	✗✓	590082	if (h261_decode_block(h, s->block[i], i, cbp & 32) < 0)
460			return SLICE_ERROR;
461		590082	cbp += cbp;
462			}
463			} else {
464	✓✓	136969	for (i = 0; i < 6; i++)
465		117402	s->block_last_index[i] = -1;
466			}
467
468		117914	ff_mpv_reconstruct_mb(s, s->block);
469
470		117914	return SLICE_OK;
471			}
472
473			/**
474			* Decode the H.261 picture header.
475			* @return <0 if no startcode found
476			*/
477		306	static int h261_decode_picture_header(H261Context *h)
478			{
479		306	MpegEncContext *const s = &h->s;
480			int format, i;
481		306	uint32_t startcode = 0;
482
483	✓✗	6120	for (i = get_bits_left(&s->gb); i > 24; i -= 1) {
484		6120	startcode = ((startcode << 1) \| get_bits(&s->gb, 1)) & 0x000FFFFF;
485
486	✓✓	6120	if (startcode == 0x10)
487		306	break;
488			}
489
490	✗✓	306	if (startcode != 0x10) {
491			av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
492			return -1;
493			}
494
495			/* temporal reference */
496		306	i = get_bits(&s->gb, 5); /* picture timestamp */
497	✓✓	306	if (i < (s->picture_number & 31))
498		6	i += 32;
499		306	s->picture_number = (s->picture_number & ~31) + i;
500
501		306	s->avctx->framerate = (AVRational) { 30000, 1001 };
502
503			/* PTYPE starts here */
504		306	skip_bits1(&s->gb); /* split screen off */
505		306	skip_bits1(&s->gb); /* camera off */
506		306	skip_bits1(&s->gb); /* freeze picture release off */
507
508		306	format = get_bits1(&s->gb);
509
510			// only 2 formats possible
511	✗✓	306	if (format == 0) { // QCIF
512			s->width = 176;
513			s->height = 144;
514			s->mb_width = 11;
515			s->mb_height = 9;
516			} else { // CIF
517		306	s->width = 352;
518		306	s->height = 288;
519		306	s->mb_width = 22;
520		306	s->mb_height = 18;
521			}
522
523		306	s->mb_num = s->mb_width * s->mb_height;
524
525		306	skip_bits1(&s->gb); /* still image mode off */
526		306	skip_bits1(&s->gb); /* Reserved */
527
528			/* PEI */
529	✗✓	306	if (skip_1stop_8data_bits(&s->gb) < 0)
530			return AVERROR_INVALIDDATA;
531
532			/* H.261 has no I-frames, but if we pass AV_PICTURE_TYPE_I for the first
533			* frame, the codec crashes if it does not contain all I-blocks
534			* (e.g. when a packet is lost). */
535		306	s->pict_type = AV_PICTURE_TYPE_P;
536
537		306	h->gob_number = 0;
538		306	return 0;
539			}
540
541		3600	static int h261_decode_gob(H261Context *h)
542			{
543		3600	MpegEncContext *const s = &h->s;
544
545		3600	ff_set_qscale(s, s->qscale);
546
547			/* decode mb's */
548	✓✗	121514	while (h->current_mba <= MBA_STUFFING) {
549			int ret;
550			/* DCT & quantize */
551		121514	ret = h261_decode_mb(h);
552	✓✓	121514	if (ret < 0) {
553	✓✗	3600	if (ret == SLICE_END) {
554		3600	h261_decode_mb_skipped(h, h->current_mba, 33);
555		3600	return 0;
556			}
557			av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n",
558			s->mb_x + s->mb_y * s->mb_stride);
559			return -1;
560			}
561
562		117914	h261_decode_mb_skipped(h,
563		117914	h->current_mba - h->mba_diff,
564		117914	h->current_mba - 1);
565			}
566
567			return -1;
568			}
569
570			/**
571			* returns the number of bytes consumed for building the current frame
572			*/
573		300	static int get_consumed_bytes(MpegEncContext *s, int buf_size)
574			{
575		300	int pos = get_bits_count(&s->gb) >> 3;
576	✗✓	300	if (pos == 0)
577			pos = 1; // avoid infinite loops (i doubt that is needed but ...)
578	✓✗	300	if (pos + 10 > buf_size)
579		300	pos = buf_size; // oops ;)
580
581		300	return pos;
582			}
583
584		300	static int h261_decode_frame(AVCodecContext avctx, void data,
585			int got_frame, AVPacket avpkt)
586			{
587		300	const uint8_t *buf = avpkt->data;
588		300	int buf_size = avpkt->size;
589		300	H261Context *h = avctx->priv_data;
590		300	MpegEncContext *s = &h->s;
591			int ret;
592		300	AVFrame *pict = data;
593
594			ff_dlog(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size);
595			ff_dlog(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
596
597		300	h->gob_start_code_skipped = 0;
598
599		306	retry:
600		306	init_get_bits(&s->gb, buf, buf_size * 8);
601
602	✓✓	306	if (!s->context_initialized)
603			// we need the IDCT permutation for reading a custom matrix
604		6	ff_mpv_idct_init(s);
605
606		306	ret = h261_decode_picture_header(h);
607
608			/* skip if the header was thrashed */
609	✗✓	306	if (ret < 0) {
610			av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
611			return -1;
612			}
613
614	✓✗✗✓	306	if (s->width != avctx->coded_width \|\| s->height != avctx->coded_height) {
615			ParseContext pc = s->parse_context; // FIXME move this demuxing hack to libavformat
616			s->parse_context.buffer = 0;
617			ff_mpv_common_end(s);
618			s->parse_context = pc;
619			}
620
621	✓✓	306	if (!s->context_initialized) {
622	✗✓	6	if ((ret = ff_mpv_common_init(s)) < 0)
623			return ret;
624
625		6	ret = ff_set_dimensions(avctx, s->width, s->height);
626	✗✓	6	if (ret < 0)
627			return ret;
628
629		6	goto retry;
630			}
631
632			// for skipping the frame
633		300	s->current_picture.f->pict_type = s->pict_type;
634		300	s->current_picture.f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;
635
636	✗✓✗✗	300	if ((avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type == AV_PICTURE_TYPE_B) \|\|
637	✗✓✗✗	300	(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type != AV_PICTURE_TYPE_I) \|\|
638	✗✓	300	avctx->skip_frame >= AVDISCARD_ALL)
639			return get_consumed_bytes(s, buf_size);
640
641	✗✓	300	if (ff_mpv_frame_start(s, avctx) < 0)
642			return -1;
643
644		300	ff_mpeg_er_frame_start(s);
645
646			/* decode each macroblock */
647		300	s->mb_x = 0;
648		300	s->mb_y = 0;
649
650	✓✗✓✓	3900	while (h->gob_number < (s->mb_height == 18 ? 12 : 5)) {
651	✗✓	3600	if (h261_resync(h) < 0)
652			break;
653		3600	h261_decode_gob(h);
654			}
655		300	ff_mpv_frame_end(s);
656
657	✗✓	300	av_assert0(s->current_picture.f->pict_type == s->current_picture_ptr->f->pict_type);
658	✗✓	300	av_assert0(s->current_picture.f->pict_type == s->pict_type);
659
660	✗✓	300	if ((ret = av_frame_ref(pict, s->current_picture_ptr->f)) < 0)
661			return ret;
662		300	ff_print_debug_info(s, s->current_picture_ptr, pict);
663
664		300	*got_frame = 1;
665
666		300	return get_consumed_bytes(s, buf_size);
667			}
668
669		13	static av_cold int h261_decode_end(AVCodecContext *avctx)
670			{
671		13	H261Context *h = avctx->priv_data;
672		13	MpegEncContext *s = &h->s;
673
674		13	ff_mpv_common_end(s);
675		13	return 0;
676			}
677
678			AVCodec ff_h261_decoder = {
679			.name = "h261",
680			.long_name = NULL_IF_CONFIG_SMALL("H.261"),
681			.type = AVMEDIA_TYPE_VIDEO,
682			.id = AV_CODEC_ID_H261,
683			.priv_data_size = sizeof(H261Context),
684			.init = h261_decode_init,
685			.close = h261_decode_end,
686			.decode = h261_decode_frame,
687			.capabilities = AV_CODEC_CAP_DR1,
688			.caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
689			.max_lowres = 3,
690			};