C++ bytestream2_skip函数代码示例

static int tgq_decode_mb(TgqContext *s, AVFrame *frame, int mb_y, int mb_x)
{
    int mode;
    int i;
    int8_t dc[6];

    mode = bytestream2_get_byte(&s->gb);
    if (mode > 12) {
        GetBitContext gb;
        init_get_bits8(&gb, s->gb.buffer, FFMIN(bytestream2_get_bytes_left(&s->gb), mode));
        for (i = 0; i < 6; i++)
            tgq_decode_block(s, s->block[i], &gb);
        tgq_idct_put_mb(s, s->block, frame, mb_x, mb_y);
        bytestream2_skip(&s->gb, mode);
    } else {
        if (mode == 3) {
            memset(dc, bytestream2_get_byte(&s->gb), 4);
            dc[4] = bytestream2_get_byte(&s->gb);
            dc[5] = bytestream2_get_byte(&s->gb);
        } else if (mode == 6) {
            bytestream2_get_buffer(&s->gb, dc, 6);
        } else if (mode == 12) {
            for (i = 0; i < 6; i++) {
                dc[i] = bytestream2_get_byte(&s->gb);
                bytestream2_skip(&s->gb, 1);
            }
        } else {
            av_log(s->avctx, AV_LOG_ERROR, "unsupported mb mode %i\n", mode);
            return -1;
        }
        tgq_idct_put_mb_dconly(s, frame, mb_x, mb_y, dc);
    }
    return 0;
}

/*
 * To be a valid APNG file, we mandate, in this order:
 *     PNGSIG
 *     IHDR
 *     ...
 *     acTL
 *     ...
 *     IDAT
 */
static int apng_probe(AVProbeData *p)
{
    GetByteContext gb;
    int state = 0;
    uint32_t len, tag;

    bytestream2_init(&gb, p->buf, p->buf_size);

    if (bytestream2_get_be64(&gb) != PNGSIG)
        return 0;

    for (;;) {
        len = bytestream2_get_be32(&gb);
        if (len > 0x7fffffff)
            return 0;

        tag = bytestream2_get_le32(&gb);
        /* we don't check IDAT size, as this is the last tag
         * we check, and it may be larger than the probe buffer */
        if (tag != MKTAG('I', 'D', 'A', 'T') &&
            len > bytestream2_get_bytes_left(&gb))
            return 0;

        switch (tag) {
        case MKTAG('I', 'H', 'D', 'R'):
            if (len != 13)
                return 0;
            if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
                return 0;
            bytestream2_skip(&gb, 9);
            state++;
            break;
        case MKTAG('a', 'c', 'T', 'L'):
            if (state != 1 ||
                len != 8 ||
                bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
                return 0;
            bytestream2_skip(&gb, 8);
            state++;
            break;
        case MKTAG('I', 'D', 'A', 'T'):
            if (state != 2)
                return 0;
            goto end;
        default:
            /* skip other tags */
            bytestream2_skip(&gb, len + 4);
            break;
        }
    }

end:
    return AVPROBE_SCORE_MAX;
}

/**
 * Read an uncompressed SGI image.
 * @param out_buf output buffer
 * @param s the current image state
 * @return 0 if read success, otherwise return -1.
 */
static int read_uncompressed_sgi(unsigned char *out_buf, SgiState *s)
{
    int x, y, z;
    unsigned int offset = s->height * s->width * s->bytes_per_channel;
    GetByteContext gp[4];
    uint8_t *out_end;

    /* Test buffer size. */
    if (offset * s->depth > bytestream2_get_bytes_left(&s->g))
        return AVERROR_INVALIDDATA;

    /* Create a reader for each plane */
    for (z = 0; z < s->depth; z++) {
        gp[z] = s->g;
        bytestream2_skip(&gp[z], z * offset);
    }

    for (y = s->height - 1; y >= 0; y--) {
        out_end = out_buf + (y * s->linesize);
        if (s->bytes_per_channel == 1) {
            for (x = s->width; x > 0; x--)
                for (z = 0; z < s->depth; z++)
                    *out_end++ = bytestream2_get_byteu(&gp[z]);
        } else {
            uint16_t *out16 = (uint16_t *)out_end;
            for (x = s->width; x > 0; x--)
                for (z = 0; z < s->depth; z++)
                    *out16++ = bytestream2_get_ne16u(&gp[z]);
        }
    }
    return 0;
}

static int pix_decode_header(PixHeader *out, GetByteContext *pgb)
{
    unsigned int header_len = bytestream2_get_be32(pgb);

    out->format = bytestream2_get_byte(pgb);
    bytestream2_skip(pgb, 2);
    out->width  = bytestream2_get_be16(pgb);
    out->height = bytestream2_get_be16(pgb);

    // the header is at least 11 bytes long; we read the first 7
    if (header_len < 11)
        return AVERROR_INVALIDDATA;

    // skip the rest of the header
    bytestream2_skip(pgb, header_len - 7);

    return 0;
}

static int hqa_decode_frame(HQContext *ctx, AVFrame *pic, size_t data_size)
{
    GetBitContext gb;
    const int num_slices = 8;
    uint32_t slice_off[9];
    int i, slice, ret;
    int width, height, quant;
    const uint8_t *src = ctx->gbc.buffer;

    width  = bytestream2_get_be16(&ctx->gbc);
    height = bytestream2_get_be16(&ctx->gbc);

    ctx->avctx->coded_width         = FFALIGN(width,  16);
    ctx->avctx->coded_height        = FFALIGN(height, 16);
    ctx->avctx->width               = width;
    ctx->avctx->height              = height;
    ctx->avctx->bits_per_raw_sample = 8;
    ctx->avctx->pix_fmt             = AV_PIX_FMT_YUVA422P;

    av_log(ctx->avctx, AV_LOG_VERBOSE, "HQA Profile\n");

    quant = bytestream2_get_byte(&ctx->gbc);
    bytestream2_skip(&ctx->gbc, 3);
    if (quant >= NUM_HQ_QUANTS) {
        av_log(ctx->avctx, AV_LOG_ERROR,
               "Invalid quantization matrix %d.\n", quant);
        return AVERROR_INVALIDDATA;
    }

    ret = ff_get_buffer(ctx->avctx, pic, 0);
    if (ret < 0) {
        av_log(ctx->avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
        return ret;
    }

    /* Offsets are stored from HQA1 position, so adjust them accordingly. */
    for (i = 0; i < num_slices + 1; i++)
        slice_off[i] = bytestream2_get_be32(&ctx->gbc) - 4;

    for (slice = 0; slice < num_slices; slice++) {
        if (slice_off[slice] < (num_slices + 1) * 3 ||
            slice_off[slice] >= slice_off[slice + 1] ||
            slice_off[slice + 1] > data_size) {
            av_log(ctx->avctx, AV_LOG_ERROR,
                   "Invalid slice size %zu.\n", data_size);
            break;
        }
        init_get_bits(&gb, src + slice_off[slice],
                      (slice_off[slice + 1] - slice_off[slice]) * 8);

        ret = hqa_decode_slice(ctx, pic, &gb, quant, slice, width, height);
        if (ret < 0)
            return ret;
    }

    return 0;
}

static int hq_hqa_decode_frame(AVCodecContext *avctx, void *data,
                               int *got_frame, AVPacket *avpkt)
{
    HQContext *ctx = avctx->priv_data;
    AVFrame *pic = data;
    uint32_t info_tag;
    unsigned int data_size;
    int ret;
    unsigned tag;

    bytestream2_init(&ctx->gbc, avpkt->data, avpkt->size);
    if (bytestream2_get_bytes_left(&ctx->gbc) < 4 + 4) {
        av_log(avctx, AV_LOG_ERROR, "Frame is too small (%d).\n", avpkt->size);
        return AVERROR_INVALIDDATA;
    }

    info_tag = bytestream2_peek_le32(&ctx->gbc);
    if (info_tag == MKTAG('I', 'N', 'F', 'O')) {
        int info_size;
        bytestream2_skip(&ctx->gbc, 4);
        info_size = bytestream2_get_le32(&ctx->gbc);
        if (bytestream2_get_bytes_left(&ctx->gbc) < info_size) {
            av_log(avctx, AV_LOG_ERROR, "Invalid INFO size (%d).\n", info_size);
            return AVERROR_INVALIDDATA;
        }
        ff_canopus_parse_info_tag(avctx, ctx->gbc.buffer, info_size);

        bytestream2_skip(&ctx->gbc, info_size);
    }

    data_size = bytestream2_get_bytes_left(&ctx->gbc);
    if (data_size < 4) {
        av_log(avctx, AV_LOG_ERROR, "Frame is too small (%d).\n", data_size);
        return AVERROR_INVALIDDATA;
    }

    /* HQ defines dimensions and number of slices, and thus slice traversal
     * order. HQA has no size constraint and a fixed number of slices, so it
     * needs a separate scheme for it. */
    tag = bytestream2_get_le32(&ctx->gbc);
    if ((tag & 0x00FFFFFF) == (MKTAG('U', 'V', 'C', ' ') & 0x00FFFFFF)) {
        ret = hq_decode_frame(ctx, pic, tag >> 24, data_size);
    } else if (tag == MKTAG('H', 'Q', 'A', '1')) {

static void mm_decode_pal(MmContext *s)
{
    int i;

    bytestream2_skip(&s->gb, 4);
    for (i = 0; i < 128; i++) {
        s->palette[i] = 0xFFU << 24 | bytestream2_get_be24(&s->gb);
        s->palette[i+128] = s->palette[i]<<2;
    }
}

static int mm_decode_pal(MmContext *s)
{
    int i;

    bytestream2_skip(&s->gb, 4);
    for (i = 0; i < 128; i++) {
        s->palette[i] = bytestream2_get_be24(&s->gb);
        s->palette[i+128] = s->palette[i]<<2;
    }

    return 0;
}

static int tgq_decode_frame(AVCodecContext *avctx,
                            void *data, int *got_frame,
                            AVPacket *avpkt){
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    TgqContext *s = avctx->priv_data;
    int x,y;
    int big_endian;

    if (buf_size < 16) {
        av_log(avctx, AV_LOG_WARNING, "truncated header\n");
        return -1;
    }
    big_endian = AV_RL32(&buf[4]) > 0x000FFFFF;
    bytestream2_init(&s->gb, buf + 8, buf_size - 8);
    if (big_endian) {
        s->width  = bytestream2_get_be16u(&s->gb);
        s->height = bytestream2_get_be16u(&s->gb);
    } else {
        s->width  = bytestream2_get_le16u(&s->gb);
        s->height = bytestream2_get_le16u(&s->gb);
    }

    if (s->avctx->width!=s->width || s->avctx->height!=s->height) {
        avcodec_set_dimensions(s->avctx, s->width, s->height);
        if (s->frame.data[0])
            avctx->release_buffer(avctx, &s->frame);
    }
    tgq_calculate_qtable(s, bytestream2_get_byteu(&s->gb));
    bytestream2_skip(&s->gb, 3);

    if (!s->frame.data[0]) {
        s->frame.key_frame = 1;
        s->frame.pict_type = AV_PICTURE_TYPE_I;
        s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
        if (ff_get_buffer(avctx, &s->frame)) {
            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
            return -1;
        }
    }

    for (y = 0; y < FFALIGN(avctx->height, 16) >> 4; y++)
        for (x = 0; x < FFALIGN(avctx->width, 16) >> 4; x++)
            if (tgq_decode_mb(s, y, x) < 0)
                return AVERROR_INVALIDDATA;

    *got_frame = 1;
    *(AVFrame*)data = s->frame;

    return avpkt->size;
}

static int parse_palette(AVCodecContext *avctx, GetByteContext *gbc,
                         uint32_t *pal, int colors)
{
    int i;

    for (i = 0; i <= colors; i++) {
        uint8_t r, g, b;
        unsigned int idx = bytestream2_get_be16(gbc); /* color index */
        if (idx > 255) {
            av_log(avctx, AV_LOG_WARNING,
                   "Palette index out of range: %u\n", idx);
            bytestream2_skip(gbc, 6);
            continue;
        }
        r = bytestream2_get_byte(gbc);
        bytestream2_skip(gbc, 1);
        g = bytestream2_get_byte(gbc);
        bytestream2_skip(gbc, 1);
        b = bytestream2_get_byte(gbc);
        bytestream2_skip(gbc, 1);
        pal[idx] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
    }
    return 0;
}

static int tgq_decode_frame(AVCodecContext *avctx,
                            void *data, int *got_frame,
                            AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size       = avpkt->size;
    TgqContext *s      = avctx->priv_data;
    AVFrame *frame     = data;
    int x, y, ret;
    int big_endian;

    if (buf_size < 16) {
        av_log(avctx, AV_LOG_WARNING, "truncated header\n");
        return AVERROR_INVALIDDATA;
    }
    big_endian = AV_RL32(&buf[4]) > 0x000FFFFF;
    bytestream2_init(&s->gb, buf + 8, buf_size - 8);
    if (big_endian) {
        s->width  = bytestream2_get_be16u(&s->gb);
        s->height = bytestream2_get_be16u(&s->gb);
    } else {
        s->width  = bytestream2_get_le16u(&s->gb);
        s->height = bytestream2_get_le16u(&s->gb);
    }

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

    tgq_calculate_qtable(s, bytestream2_get_byteu(&s->gb));
    bytestream2_skip(&s->gb, 3);

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;
    frame->key_frame = 1;
    frame->pict_type = AV_PICTURE_TYPE_I;

    for (y = 0; y < FFALIGN(avctx->height, 16) >> 4; y++)
        for (x = 0; x < FFALIGN(avctx->width, 16) >> 4; x++)
            if (tgq_decode_mb(s, frame, y, x) < 0)
                return AVERROR_INVALIDDATA;

    *got_frame = 1;

    return avpkt->size;
}

/* There are (invalid) samples in the wild with mp4-style extradata, where the
 * parameter sets are stored unescaped (i.e. as RBSP).
 * This function catches the parameter set decoding failure and tries again
 * after escaping it */
static int decode_extradata_ps_mp4(const uint8_t *buf, int buf_size, H264ParamSets *ps,
                                   int err_recognition, void *logctx)
{
    int ret;

    ret = decode_extradata_ps(buf, buf_size, ps, 1, logctx);
    if (ret < 0 && !(err_recognition & AV_EF_EXPLODE)) {
        GetByteContext gbc;
        PutByteContext pbc;
        uint8_t *escaped_buf;
        int escaped_buf_size;

        av_log(logctx, AV_LOG_WARNING,
               "SPS decoding failure, trying again after escaping the NAL\n");

        if (buf_size / 2 >= (INT16_MAX - AV_INPUT_BUFFER_PADDING_SIZE) / 3)
            return AVERROR(ERANGE);
        escaped_buf_size = buf_size * 3 / 2 + AV_INPUT_BUFFER_PADDING_SIZE;
        escaped_buf = av_mallocz(escaped_buf_size);
        if (!escaped_buf)
            return AVERROR(ENOMEM);

        bytestream2_init(&gbc, buf, buf_size);
        bytestream2_init_writer(&pbc, escaped_buf, escaped_buf_size);

        while (bytestream2_get_bytes_left(&gbc)) {
            if (bytestream2_get_bytes_left(&gbc) >= 3 &&
                bytestream2_peek_be24(&gbc) <= 3) {
                bytestream2_put_be24(&pbc, 3);
                bytestream2_skip(&gbc, 2);
            } else
                bytestream2_put_byte(&pbc, bytestream2_get_byte(&gbc));
        }

        escaped_buf_size = bytestream2_tell_p(&pbc);
        AV_WB16(escaped_buf, escaped_buf_size - 2);

        ret = decode_extradata_ps(escaped_buf, escaped_buf_size, ps, 1, logctx);
        av_freep(&escaped_buf);
        if (ret < 0)
            return ret;
    }

    return 0;
}

static int decode_frame(AVCodecContext *avctx,
                        void *data, int *got_frame,
                        AVPacket *avpkt)
{
  AnmContext *s = avctx->priv_data;
  const int buf_size = avpkt->size;
  uint8_t *dst, *dst_end;
  int count, ret;

  if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
    return ret;
  dst     = s->frame->data[0];
  dst_end = s->frame->data[0] + s->frame->linesize[0]*avctx->height;

  bytestream2_init(&s->gb, avpkt->data, buf_size);

  if (bytestream2_get_byte(&s->gb) != 0x42) {
    avpriv_request_sample(avctx, "Unknown record type");
    return AVERROR_INVALIDDATA;
  }
  if (bytestream2_get_byte(&s->gb)) {
    avpriv_request_sample(avctx, "Padding bytes");
    return AVERROR_PATCHWELCOME;
  }
  bytestream2_skip(&s->gb, 2);

  s->x = 0;
  do {
    /* if statements are ordered by probability */
#define OP(gb, pixel, count)                                            \
    op(&dst, dst_end, (gb), (pixel), (count), &s->x, avctx->width, s->frame->linesize[0])

    int type = bytestream2_get_byte(&s->gb);
    count = type & 0x7F;
    type >>= 7;
    if (count) {
      if (OP(type ? NULL : &s->gb, -1, count)) break;
    } else if (!type) {
      int pixel;
      count = bytestream2_get_byte(&s->gb);  /* count==0 gives nop */
      pixel = bytestream2_get_byte(&s->gb);
      if (OP(NULL, pixel, count)) break;
    } else {
      int pixel;
      type = bytestream2_get_le16(&s->gb);
      count = type & 0x3FFF;
      type >>= 14;
      if (!count) {
        if (type == 0)
          break; // stop
        if (type == 2) {
          avpriv_request_sample(avctx, "Unknown opcode");
          return AVERROR_PATCHWELCOME;
        }
        continue;
      }
      pixel = type == 3 ? bytestream2_get_byte(&s->gb) : -1;
      if (type == 1) count += 0x4000;
      if (OP(type == 2 ? &s->gb : NULL, pixel, count)) break;
    }
  } while (bytestream2_get_bytes_left(&s->gb) > 0);

  memcpy(s->frame->data[1], s->palette, AVPALETTE_SIZE);

  *got_frame = 1;
  if ((ret = av_frame_ref(data, s->frame)) < 0)
    return ret;

  return buf_size;
}

static int decode_frame(AVCodecContext *avctx,
                        void *data, int *data_size,
                        AVPacket *avpkt)
{
    AnmContext *s = avctx->priv_data;
    const int buf_size = avpkt->size;
    uint8_t *dst, *dst_end;
    int count;

    if(avctx->reget_buffer(avctx, &s->frame) < 0){
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }
    dst     = s->frame.data[0];
    dst_end = s->frame.data[0] + s->frame.linesize[0]*avctx->height;

    bytestream2_init(&s->gb, avpkt->data, buf_size);

    if (bytestream2_get_byte(&s->gb) != 0x42) {
        av_log_ask_for_sample(avctx, "unknown record type\n");
        return buf_size;
    }
    if (bytestream2_get_byte(&s->gb)) {
        av_log_ask_for_sample(avctx, "padding bytes not supported\n");
        return buf_size;
    }
    bytestream2_skip(&s->gb, 2);

    s->x = 0;
    do {
        /* if statements are ordered by probability */
#define OP(gb, pixel, count) \
    op(&dst, dst_end, (gb), (pixel), (count), &s->x, avctx->width, s->frame.linesize[0])

        int type = bytestream2_get_byte(&s->gb);
        count = type & 0x7F;
        type >>= 7;
        if (count) {
            if (OP(type ? NULL : &s->gb, -1, count)) break;
        } else if (!type) {
            int pixel;
            count = bytestream2_get_byte(&s->gb);  /* count==0 gives nop */
            pixel = bytestream2_get_byte(&s->gb);
            if (OP(NULL, pixel, count)) break;
        } else {
            int pixel;
            type = bytestream2_get_le16(&s->gb);
            count = type & 0x3FFF;
            type >>= 14;
            if (!count) {
                if (type == 0)
                    break; // stop
                if (type == 2) {
                    av_log_ask_for_sample(avctx, "unknown opcode");
                    return AVERROR_INVALIDDATA;
                }
                continue;
            }
            pixel = type == 3 ? bytestream2_get_byte(&s->gb) : -1;
            if (type == 1) count += 0x4000;
            if (OP(type == 2 ? &s->gb : NULL, pixel, count)) break;
        }
    } while (bytestream2_get_bytes_left(&s->gb) > 0);

    memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);

    *data_size = sizeof(AVFrame);
    *(AVFrame*)data = s->frame;
    return buf_size;
}

static int flic_decode_frame_8BPP(AVCodecContext *avctx,
                                  void *data, int *data_size,
                                  const uint8_t *buf, int buf_size)
{
    FlicDecodeContext *s = avctx->priv_data;

    GetByteContext g2;
    int pixel_ptr;
    int palette_ptr;
    unsigned char palette_idx1;
    unsigned char palette_idx2;

    unsigned int frame_size;
    int num_chunks;

    unsigned int chunk_size;
    int chunk_type;

    int i, j;

    int color_packets;
    int color_changes;
    int color_shift;
    unsigned char r, g, b;

    int lines;
    int compressed_lines;
    int starting_line;
    signed short line_packets;
    int y_ptr;
    int byte_run;
    int pixel_skip;
    int pixel_countdown;
    unsigned char *pixels;
    unsigned int pixel_limit;

    bytestream2_init(&g2, buf, buf_size);

    s->frame.reference = 3;
    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
    if (avctx->reget_buffer(avctx, &s->frame) < 0) {
        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return -1;
    }

    pixels = s->frame.data[0];
    pixel_limit = s->avctx->height * s->frame.linesize[0];
    if (buf_size < 16 || buf_size > INT_MAX - (3 * 256 + FF_INPUT_BUFFER_PADDING_SIZE))
        return AVERROR_INVALIDDATA;
    frame_size = bytestream2_get_le32(&g2);
    if (frame_size > buf_size)
        frame_size = buf_size;
    bytestream2_skip(&g2, 2); /* skip the magic number */
    num_chunks = bytestream2_get_le16(&g2);
    bytestream2_skip(&g2, 8);  /* skip padding */

    frame_size -= 16;

    /* iterate through the chunks */
    while ((frame_size >= 6) && (num_chunks > 0)) {
        int stream_ptr_after_chunk;
        chunk_size = bytestream2_get_le32(&g2);
        if (chunk_size > frame_size) {
            av_log(avctx, AV_LOG_WARNING,
                   "Invalid chunk_size = %u > frame_size = %u\n", chunk_size, frame_size);
            chunk_size = frame_size;
        }
        stream_ptr_after_chunk = bytestream2_tell(&g2) - 4 + chunk_size;

        chunk_type = bytestream2_get_le16(&g2);

        switch (chunk_type) {
        case FLI_256_COLOR:
        case FLI_COLOR:
            /* check special case: If this file is from the Magic Carpet
             * game and uses 6-bit colors even though it reports 256-color
             * chunks in a 0xAF12-type file (fli_type is set to 0xAF13 during
             * initialization) */
            if ((chunk_type == FLI_256_COLOR) && (s->fli_type != FLC_MAGIC_CARPET_SYNTHETIC_TYPE_CODE))
                color_shift = 0;
            else
                color_shift = 2;
            /* set up the palette */
            color_packets = bytestream2_get_le16(&g2);
            palette_ptr = 0;
            for (i = 0; i < color_packets; i++) {
                /* first byte is how many colors to skip */
                palette_ptr += bytestream2_get_byte(&g2);

                /* next byte indicates how many entries to change */
                color_changes = bytestream2_get_byte(&g2);

                /* if there are 0 color changes, there are actually 256 */
                if (color_changes == 0)
                    color_changes = 256;

                if (bytestream2_tell(&g2) + color_changes * 3 > stream_ptr_after_chunk)
                    break;

                for (j = 0; j < color_changes; j++) {
//.........这里部分代码省略.........