GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/mpeg4_unpack_bframes_bsf.c Lines: 63 70 90.0 %
Date: 2019-11-22 03:34:36 Branches: 40 50 80.0 %

Line Branch Exec Source
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/*
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 * Bitstream filter for unpacking DivX-style packed B-frames in MPEG-4 (divx_packed)
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 * Copyright (c) 2015 Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "avcodec.h"
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#include "bsf.h"
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#include "internal.h"
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#include "mpeg4video.h"
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typedef struct UnpackBFramesBSFContext {
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    AVBufferRef *b_frame_ref;
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} UnpackBFramesBSFContext;
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/* determine the position of the packed marker in the userdata,
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 * the number of VOPs and the position of the second VOP */
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16
static void scan_buffer(const uint8_t *buf, int buf_size,
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                        int *pos_p, int *nb_vop, int *pos_vop2) {
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    uint32_t startcode;
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16
    const uint8_t *end = buf + buf_size, *pos = buf;
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64
    while (pos < end) {
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48
        startcode = -1;
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48
        pos = avpriv_find_start_code(pos, end, &startcode);
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42

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        if (startcode == USER_DATA_STARTCODE && pos_p) {
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            /* check if the (DivX) userdata string ends with 'p' (packed) */
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            for (int i = 0; i < 255 && pos + i + 1 < end; i++) {
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                if (pos[i] == 'p' && pos[i + 1] == '\0') {
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2
                    *pos_p = pos + i - buf;
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2
                    break;
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                }
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            }
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44
        } else if (startcode == VOP_STARTCODE && nb_vop) {
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20
            *nb_vop += 1;
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20
            if (*nb_vop == 2 && pos_vop2) {
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5
                *pos_vop2 = pos - buf - 4; /* subtract 4 bytes startcode */
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            }
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        }
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    }
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16
}
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static int mpeg4_unpack_bframes_filter(AVBSFContext *ctx, AVPacket *pkt)
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{
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30
    UnpackBFramesBSFContext *s = ctx->priv_data;
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30
    int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0;
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64
30
    ret = ff_bsf_get_packet_ref(ctx, pkt);
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30
    if (ret < 0)
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15
        return ret;
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15
    scan_buffer(pkt->data, pkt->size, &pos_p, &nb_vop, &pos_vop2);
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15
    av_log(ctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop);
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15
    if (pos_vop2 >= 0) {
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5
        if (s->b_frame_ref) {
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            av_log(ctx, AV_LOG_WARNING,
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                   "Missing one N-VOP packet, discarding one B-frame.\n");
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            av_buffer_unref(&s->b_frame_ref);
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        }
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        /* store a reference to the packed B-frame's data in the BSFContext */
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5
        s->b_frame_ref = av_buffer_ref(pkt->buf);
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5
        if (!s->b_frame_ref) {
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            ret = AVERROR(ENOMEM);
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            goto fail;
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        }
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5
        s->b_frame_ref->data = pkt->data + pos_vop2;
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5
        s->b_frame_ref->size = pkt->size - pos_vop2;
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    }
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    if (nb_vop > 2) {
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        av_log(ctx, AV_LOG_WARNING,
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       "Found %d VOP headers in one packet, only unpacking one.\n", nb_vop);
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    }
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    if (nb_vop == 1 && s->b_frame_ref) {
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7
        AVBufferRef *tmp = pkt->buf;
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        /* make tmp accurately reflect the packet's data */
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7
        tmp->data = pkt->data;
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        tmp->size = pkt->size;
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        /* replace data in packet with stored data */
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7
        pkt->buf  = s->b_frame_ref;
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        pkt->data = s->b_frame_ref->data;
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        pkt->size = s->b_frame_ref->size;
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        /* store reference to data into BSFContext */
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        s->b_frame_ref = tmp;
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        if (s->b_frame_ref->size <= MAX_NVOP_SIZE) {
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            /* N-VOP - discard stored data */
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4
            av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n");
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4
            av_buffer_unref(&s->b_frame_ref);
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        }
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    } else if (nb_vop >= 2) {
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        /* use first frame of the packet */
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5
        pkt->size = pos_vop2;
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3
    } else if (pos_p >= 0) {
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1
        ret = av_packet_make_writable(pkt);
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1
        if (ret < 0)
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            goto fail;
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1
        av_log(ctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n");
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        /* remove 'p' (packed) from the end of the (DivX) userdata string */
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1
        pkt->data[pos_p] = '\0';
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    } else {
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        /* use packet as is */
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    }
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fail:
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    if (ret < 0)
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        av_packet_unref(pkt);
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    return ret;
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}
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1
static int mpeg4_unpack_bframes_init(AVBSFContext *ctx)
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{
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1
    if (ctx->par_in->extradata) {
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1
        int pos_p_ext = -1;
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1
        scan_buffer(ctx->par_in->extradata, ctx->par_in->extradata_size, &pos_p_ext, NULL, NULL);
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1
        if (pos_p_ext >= 0) {
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1
            av_log(ctx, AV_LOG_DEBUG,
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                   "Updating DivX userdata (remove trailing 'p') in extradata.\n");
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1
            ctx->par_out->extradata[pos_p_ext] = '\0';
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        }
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    }
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    return 0;
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}
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static void mpeg4_unpack_bframes_close_flush(AVBSFContext *bsfc)
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{
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1
    UnpackBFramesBSFContext *ctx = bsfc->priv_data;
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1
    av_buffer_unref(&ctx->b_frame_ref);
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1
}
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static const enum AVCodecID codec_ids[] = {
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    AV_CODEC_ID_MPEG4, AV_CODEC_ID_NONE,
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};
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const AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf = {
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    .name           = "mpeg4_unpack_bframes",
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    .priv_data_size = sizeof(UnpackBFramesBSFContext),
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    .init           = mpeg4_unpack_bframes_init,
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    .filter         = mpeg4_unpack_bframes_filter,
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    .flush          = mpeg4_unpack_bframes_close_flush,
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    .close          = mpeg4_unpack_bframes_close_flush,
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    .codec_ids      = codec_ids,
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};