[x264-devel] [PATCH] PSNR averages
Loren Merritt
lorenm at u.washington.edu
Sun Aug 8 05:59:57 CEST 2004
x264 takes the arithmetic mean of frame-wise PSNRs to produce an
overall PSNR. This is meaningless. (Extreme case: what do you do with a
frame with no error? (infinite PSNR))
This patch corrects it to calculate PSNR from the mean squared error.
I also replace "PSNR/Size" (which is similarly meaningless) with
"MSE*Size". This quantity is probably closer to what someone wants to
measure when they think of "PSNR/Size". It also tends to be relatively
constant for a given video over a wide range of QPs.)
--Loren Merritt
-------------- next part --------------
Index: core/common.h
===================================================================
--- core/common.h (revision 18)
+++ core/common.h (working copy)
@@ -324,9 +324,9 @@
/* per slice info */
int i_slice_count[5];
int i_slice_size[5];
- float f_psnr_y[5];
- float f_psnr_u[5];
- float f_psnr_v[5];
+ float f_mse_y[5];
+ float f_mse_u[5];
+ float f_mse_v[5];
int i_mb_count[5][18];
} stat;
Index: encoder/encoder.c
===================================================================
--- encoder/encoder.c (revision 18)
+++ encoder/encoder.c (working copy)
@@ -60,7 +60,7 @@
****************************************************************************/
-static float x264_psnr( uint8_t *pix1, int i_pix_stride, uint8_t *pix2, int i_pix2_stride, int i_width, int i_height )
+static float x264_mse( uint8_t *pix1, int i_pix_stride, uint8_t *pix2, int i_pix2_stride, int i_width, int i_height )
{
int64_t i_sqe = 0;
@@ -78,13 +78,14 @@
}
}
- if( i_sqe == 0 )
- {
- return -1.0;
- }
- return (float)(10.0 * log( (double)65025.0 * (double)i_height * (double)i_width / (double)i_sqe ) / log( 10.0 ));
+ return (double)i_sqe / ((double)65025.0 * (double)i_height * (double)i_width);
}
+static float x264_psnr( float mse )
+{
+ return (float)(-10.0 * log( mse ) / log( 10.0 ));
+}
+
#if DEBUG_DUMP_FRAME
static void x264_frame_dump( x264_t *h, x264_frame_t *fr, char *name )
{
@@ -409,9 +410,9 @@
h->stat.i_slice_size[SLICE_TYPE_P] = 0;
h->stat.i_slice_size[SLICE_TYPE_B] = 0;
- h->stat.f_psnr_y[SLICE_TYPE_I] = 0.0; h->stat.f_psnr_u[SLICE_TYPE_I] = 0.0; h->stat.f_psnr_v[SLICE_TYPE_I] = 0.0;
- h->stat.f_psnr_y[SLICE_TYPE_P] = 0.0; h->stat.f_psnr_u[SLICE_TYPE_P] = 0.0; h->stat.f_psnr_v[SLICE_TYPE_P] = 0.0;
- h->stat.f_psnr_y[SLICE_TYPE_B] = 0.0; h->stat.f_psnr_u[SLICE_TYPE_B] = 0.0; h->stat.f_psnr_v[SLICE_TYPE_B] = 0.0;
+ h->stat.f_mse_y[SLICE_TYPE_I] = 0.0; h->stat.f_mse_u[SLICE_TYPE_I] = 0.0; h->stat.f_mse_v[SLICE_TYPE_I] = 0.0;
+ h->stat.f_mse_y[SLICE_TYPE_P] = 0.0; h->stat.f_mse_u[SLICE_TYPE_P] = 0.0; h->stat.f_mse_v[SLICE_TYPE_P] = 0.0;
+ h->stat.f_mse_y[SLICE_TYPE_B] = 0.0; h->stat.f_mse_u[SLICE_TYPE_B] = 0.0; h->stat.f_mse_v[SLICE_TYPE_B] = 0.0;
for( i = 0; i < 17; i++ )
{
@@ -799,14 +800,14 @@
x264_nal_t **pp_nal, int *pi_nal,
x264_picture_t *pic )
{
- x264_frame_t *frame_psnr = h->fdec; /* just to kept the current decoded frame for psnr calculation */
+ x264_frame_t *frame_psnr = h->fdec; /* just to keep the current decoded frame for psnr calculation */
int i_nal_type;
int i_nal_ref_idc;
int i_slice_type;
int i;
- float psnr_y, psnr_u, psnr_v;
+ float mse_y, mse_u, mse_v;
int i_global_qp;
@@ -1123,16 +1124,16 @@
/* ---------------------- Compute/Print statistics --------------------- */
/* PSNR */
- psnr_y = x264_psnr( frame_psnr->plane[0], frame_psnr->i_stride[0], h->fenc->plane[0], h->fenc->i_stride[0], h->param.i_width, h->param.i_height );
- psnr_u = x264_psnr( frame_psnr->plane[1], frame_psnr->i_stride[1], h->fenc->plane[1], h->fenc->i_stride[1], h->param.i_width/2, h->param.i_height/2);
- psnr_v = x264_psnr( frame_psnr->plane[2], frame_psnr->i_stride[2], h->fenc->plane[2], h->fenc->i_stride[2], h->param.i_width/2, h->param.i_height/2);
+ mse_y = x264_mse( frame_psnr->plane[0], frame_psnr->i_stride[0], h->fenc->plane[0], h->fenc->i_stride[0], h->param.i_width, h->param.i_height );
+ mse_u = x264_mse( frame_psnr->plane[1], frame_psnr->i_stride[1], h->fenc->plane[1], h->fenc->i_stride[1], h->param.i_width/2, h->param.i_height/2);
+ mse_v = x264_mse( frame_psnr->plane[2], frame_psnr->i_stride[2], h->fenc->plane[2], h->fenc->i_stride[2], h->param.i_width/2, h->param.i_height/2);
/* Slice stat */
h->stat.i_slice_count[i_slice_type]++;
h->stat.i_slice_size[i_slice_type] += bs_pos( &h->out.bs) / 8;
- h->stat.f_psnr_y[i_slice_type] += psnr_y;
- h->stat.f_psnr_u[i_slice_type] += psnr_u;
- h->stat.f_psnr_v[i_slice_type] += psnr_v;
+ h->stat.f_mse_y[i_slice_type] += mse_y;
+ h->stat.f_mse_u[i_slice_type] += mse_u;
+ h->stat.f_mse_v[i_slice_type] += mse_v;
for( i = 0; i < 17; i++ )
{
@@ -1151,7 +1152,7 @@
i_mb_count[P_L0] + i_mb_count[P_8x8],
i_mb_count[P_SKIP],
h->out.nal[h->out.i_nal-1].i_payload,
- psnr_y, psnr_u, psnr_v );
+ x264_psnr(mse_y), x264_psnr(mse_u), x264_psnr(mse_v) );
#ifdef DEBUG_MB_TYPE
for( mb_xy = 0; mb_xy < h->sps->i_mb_width * h->sps->i_mb_height; mb_xy++ )
{
@@ -1213,34 +1214,35 @@
if( h->stat.i_slice_count[SLICE_TYPE_I] > 0 )
{
const int i_count = h->stat.i_slice_count[SLICE_TYPE_I];
- fprintf( stderr, "x264: slice I:%-4d Avg size:%-5d PSNR Y:%2.2f U:%2.2f V:%2.2f PSNR-Y/Size:%2.2f\n",
+ fprintf( stderr, "x264: slice I:%-4d Avg size:%-5d PSNR Y:%5.2f U:%5.2f V:%5.2f MSE-Y*Size:%5.3f\n",
i_count,
h->stat.i_slice_size[SLICE_TYPE_I] / i_count,
- h->stat.f_psnr_y[SLICE_TYPE_I] / i_count,
- h->stat.f_psnr_u[SLICE_TYPE_I] / i_count,
- h->stat.f_psnr_v[SLICE_TYPE_I] / i_count,
- 1000*h->stat.f_psnr_y[SLICE_TYPE_I] / h->stat.i_slice_size[SLICE_TYPE_I] );
+ x264_psnr(h->stat.f_mse_y[SLICE_TYPE_I] / i_count),
+ x264_psnr(h->stat.f_mse_u[SLICE_TYPE_I] / i_count),
+ x264_psnr(h->stat.f_mse_v[SLICE_TYPE_I] / i_count),
+ (h->stat.f_mse_y[SLICE_TYPE_I] / i_count) * h->stat.i_slice_size[SLICE_TYPE_I] / i_count );
}
if( h->stat.i_slice_count[SLICE_TYPE_P] > 0 )
{
const int i_count = h->stat.i_slice_count[SLICE_TYPE_P];
- fprintf( stderr, "x264: slice P:%-4d Avg size:%-5d PSNR Y:%2.2f U:%2.2f V:%2.2f PSNR-Y/Size:%2.2f\n",
- i_count,
- h->stat.i_slice_size[SLICE_TYPE_P] / i_count,
- h->stat.f_psnr_y[SLICE_TYPE_P] / i_count,
- h->stat.f_psnr_u[SLICE_TYPE_P] / i_count,
- h->stat.f_psnr_v[SLICE_TYPE_P] / i_count,
- 1000.0*h->stat.f_psnr_y[SLICE_TYPE_P] / h->stat.i_slice_size[SLICE_TYPE_P] );
+ fprintf( stderr, "x264: slice P:%-4d Avg size:%-5d PSNR Y:%5.2f U:%5.2f V:%5.2f MSE-Y*Size:%5.3f\n",
+ i_count,
+ h->stat.i_slice_size[SLICE_TYPE_P] / i_count,
+ x264_psnr(h->stat.f_mse_y[SLICE_TYPE_P] / i_count),
+ x264_psnr(h->stat.f_mse_u[SLICE_TYPE_P] / i_count),
+ x264_psnr(h->stat.f_mse_v[SLICE_TYPE_P] / i_count),
+ (h->stat.f_mse_y[SLICE_TYPE_P] / i_count) * h->stat.i_slice_size[SLICE_TYPE_P] / i_count );
}
if( h->stat.i_slice_count[SLICE_TYPE_B] > 0 )
{
- fprintf( stderr, "x264: slice B:%-4d Avg size:%-5d PSNR Y:%2.2f U:%2.2f V:%2.2f PSNR-Y/Size:%2.2f\n",
- h->stat.i_slice_count[SLICE_TYPE_B],
- h->stat.i_slice_size[SLICE_TYPE_B] / h->stat.i_slice_count[SLICE_TYPE_B],
- h->stat.f_psnr_y[SLICE_TYPE_B] / h->stat.i_slice_count[SLICE_TYPE_B],
- h->stat.f_psnr_u[SLICE_TYPE_B] / h->stat.i_slice_count[SLICE_TYPE_B],
- h->stat.f_psnr_v[SLICE_TYPE_B] / h->stat.i_slice_count[SLICE_TYPE_B],
- 1000*h->stat.f_psnr_y[SLICE_TYPE_B] / h->stat.i_slice_size[SLICE_TYPE_B] );
+ const int i_count = h->stat.i_slice_count[SLICE_TYPE_B];
+ fprintf( stderr, "x264: slice B:%-4d Avg size:%-5d PSNR Y:%5.2f U:%5.2f V:%5.2f MSE-Y*Size:%5.3f\n",
+ h->stat.i_slice_count[SLICE_TYPE_B],
+ h->stat.i_slice_size[SLICE_TYPE_B] / i_count,
+ x264_psnr(h->stat.f_mse_y[SLICE_TYPE_B] / i_count),
+ x264_psnr(h->stat.f_mse_u[SLICE_TYPE_B] / i_count),
+ x264_psnr(h->stat.f_mse_v[SLICE_TYPE_B] / i_count),
+ (h->stat.f_mse_y[SLICE_TYPE_B] / i_count) * h->stat.i_slice_size[SLICE_TYPE_B] / i_count );
}
/* MB types used */
@@ -1267,10 +1269,10 @@
h->stat.i_slice_count[SLICE_TYPE_P] +
h->stat.i_slice_count[SLICE_TYPE_B];
- fprintf( stderr, "x264: overall PSNR Y:%2.2f U:%2.2f V:%2.2f kb/s:%.1f fps:%.3f\n",
- (h->stat.f_psnr_y[SLICE_TYPE_I]+h->stat.f_psnr_y[SLICE_TYPE_P]+h->stat.f_psnr_y[SLICE_TYPE_B]) / i_count,
- (h->stat.f_psnr_u[SLICE_TYPE_I]+h->stat.f_psnr_u[SLICE_TYPE_P]+h->stat.f_psnr_u[SLICE_TYPE_B]) / i_count,
- (h->stat.f_psnr_v[SLICE_TYPE_I]+h->stat.f_psnr_v[SLICE_TYPE_P]+h->stat.f_psnr_v[SLICE_TYPE_B]) / i_count,
+ fprintf( stderr, "x264: overall PSNR Y:%5.2f U:%5.2f V:%5.2f kb/s:%.1f fps:%.3f\n",
+ x264_psnr( (h->stat.f_mse_y[SLICE_TYPE_I]+h->stat.f_mse_y[SLICE_TYPE_P]+h->stat.f_mse_y[SLICE_TYPE_B]) / i_count ),
+ x264_psnr( (h->stat.f_mse_u[SLICE_TYPE_I]+h->stat.f_mse_u[SLICE_TYPE_P]+h->stat.f_mse_u[SLICE_TYPE_B]) / i_count ),
+ x264_psnr( (h->stat.f_mse_v[SLICE_TYPE_I]+h->stat.f_mse_v[SLICE_TYPE_P]+h->stat.f_mse_v[SLICE_TYPE_B]) / i_count ),
h->param.f_fps * 8*(h->stat.i_slice_size[SLICE_TYPE_I]+h->stat.i_slice_size[SLICE_TYPE_P]+h->stat.i_slice_size[SLICE_TYPE_B]) / i_count / 1024,
(double)1000000.0 * (double)i_count / (double)i_mtime_encode_frame );
}
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