generic-library/ffmpeg
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warn the user if the quantization code could overflow with the selected custom matrix and qp limits

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Originally committed as revision 3747 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2004-12-11 18:33:18 +00:00
parent bf835aee11
commit 732ce18eab
1 changed files with 14 additions and 4 deletions
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18
libavcodec/mpegvideo.c
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@ -109,9 +109,10 @@ static uint8_t default_fcode_tab[MAX_MV*2+1];
enum PixelFormat ff_yuv420p_list[2]= {PIX_FMT_YUV420P, -1};
static void convert_matrix(DSPContext *dsp, int (*qmat)[64], uint16_t (*qmat16)[2][64],
const uint16_t *quant_matrix, int bias, int qmin, int qmax)
const uint16_t *quant_matrix, int bias, int qmin, int qmax, int intra)
{
int qscale;
int shift=0;
for(qscale=qmin; qscale<=qmax; qscale++){
int i;
@ -161,6 +162,15 @@ static void convert_matrix(DSPContext *dsp, int (*qmat)[64], uint16_t (*qmat16)[
qmat16[qscale][1][i]= ROUNDED_DIV(bias<<(16-QUANT_BIAS_SHIFT), qmat16[qscale][0][i]);
}
}
for(i=intra; i<64; i++){
while(((8191LL * qmat[qscale][i]) >> shift) > INT_MAX){
shift++;
}
}
}
if(shift){
av_log(NULL, AV_LOG_INFO, "Warning, QMAT_SHIFT is larger then %d, overflows possible\n", QMAT_SHIFT - shift);
}
}
@ -1246,9 +1256,9 @@ int MPV_encode_init(AVCodecContext *avctx)
/* for mjpeg, we do include qscale in the matrix */
if (s->out_format != FMT_MJPEG) {
convert_matrix(&s->dsp, s->q_intra_matrix, s->q_intra_matrix16,
s->intra_matrix, s->intra_quant_bias, 1, 31);
s->intra_matrix, s->intra_quant_bias, avctx->qmin, 31, 1);
convert_matrix(&s->dsp, s->q_inter_matrix, s->q_inter_matrix16,
s->inter_matrix, s->inter_quant_bias, 1, 31);
s->inter_matrix, s->inter_quant_bias, avctx->qmin, 31, 0);
}
if(ff_rate_control_init(s) < 0)
@ -5290,7 +5300,7 @@ static void encode_picture(MpegEncContext *s, int picture_number)
s->intra_matrix[j] = CLAMP_TO_8BIT((ff_mpeg1_default_intra_matrix[i] * s->qscale) >> 3);
}
convert_matrix(&s->dsp, s->q_intra_matrix, s->q_intra_matrix16,
s->intra_matrix, s->intra_quant_bias, 8, 8);
s->intra_matrix, s->intra_quant_bias, 8, 8, 1);
s->qscale= 8;
}