The RSHIFT macro in libavutil/common.h does not actually perform a bitwise right-shift, but rather a rounded version of the same operation, as is noted by a comment above the macro. The rounded divsion macro on the very next line is named ROUNDED_DIV, which seems far more clear.
This patch renames RSHIFT to ROUNDED_RSHIFT, then updates all uses of the macro to use the new name. (These are all located in three codec files under libavcodec/.) Signed-off-by: FeRD (Frank Dana) <ferd...@gmail.com> --- libavcodec/mpeg4videodec.c | 4 ++-- libavcodec/vp3.c | 16 ++++++++-------- libavcodec/vp56.c | 4 ++-- libavutil/common.h | 2 +- 4 files changed, 13 insertions(+), 13 deletions(-) diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c index f44ee76bd4..5d63ba12ba 100644 --- a/libavcodec/mpeg4videodec.c +++ b/libavcodec/mpeg4videodec.c @@ -601,7 +601,7 @@ static inline int get_amv(Mpeg4DecContext *ctx, int n) if (ctx->divx_version == 500 && ctx->divx_build == 413 && a >= s->quarter_sample) sum = s->sprite_offset[0][n] / (1 << (a - s->quarter_sample)); else - sum = RSHIFT(s->sprite_offset[0][n] * (1 << s->quarter_sample), a); + sum = ROUNDED_RSHIFT(s->sprite_offset[0][n] * (1 << s->quarter_sample), a); } else { dx = s->sprite_delta[n][0]; dy = s->sprite_delta[n][1]; @@ -623,7 +623,7 @@ static inline int get_amv(Mpeg4DecContext *ctx, int n) v += dx; } } - sum = RSHIFT(sum, a + 8 - s->quarter_sample); + sum = ROUNDED_RSHIFT(sum, a + 8 - s->quarter_sample); } if (sum < -len) diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c index a5d8c2ed0b..13b3d6e22a 100644 --- a/libavcodec/vp3.c +++ b/libavcodec/vp3.c @@ -861,10 +861,10 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb) if (s->chroma_y_shift) { if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) { - motion_x[0] = RSHIFT(motion_x[0] + motion_x[1] + - motion_x[2] + motion_x[3], 2); - motion_y[0] = RSHIFT(motion_y[0] + motion_y[1] + - motion_y[2] + motion_y[3], 2); + motion_x[0] = ROUNDED_RSHIFT(motion_x[0] + motion_x[1] + + motion_x[2] + motion_x[3], 2); + motion_y[0] = ROUNDED_RSHIFT(motion_y[0] + motion_y[1] + + motion_y[2] + motion_y[3], 2); } motion_x[0] = (motion_x[0] >> 1) | (motion_x[0] & 1); motion_y[0] = (motion_y[0] >> 1) | (motion_y[0] & 1); @@ -873,10 +873,10 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb) s->motion_val[1][frag][1] = motion_y[0]; } else if (s->chroma_x_shift) { if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) { - motion_x[0] = RSHIFT(motion_x[0] + motion_x[1], 1); - motion_y[0] = RSHIFT(motion_y[0] + motion_y[1], 1); - motion_x[1] = RSHIFT(motion_x[2] + motion_x[3], 1); - motion_y[1] = RSHIFT(motion_y[2] + motion_y[3], 1); + motion_x[0] = ROUNDED_RSHIFT(motion_x[0] + motion_x[1], 1); + motion_y[0] = ROUNDED_RSHIFT(motion_y[0] + motion_y[1], 1); + motion_x[1] = ROUNDED_RSHIFT(motion_x[2] + motion_x[3], 1); + motion_y[1] = ROUNDED_RSHIFT(motion_y[2] + motion_y[3], 1); } else { motion_x[1] = motion_x[0]; motion_y[1] = motion_y[0]; diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c index b69fe6c176..9359b48bc6 100644 --- a/libavcodec/vp56.c +++ b/libavcodec/vp56.c @@ -197,8 +197,8 @@ static void vp56_decode_4mv(VP56Context *s, int row, int col) /* chroma vectors are average luma vectors */ if (s->avctx->codec->id == AV_CODEC_ID_VP5) { - s->mv[4].x = s->mv[5].x = RSHIFT(mv.x,2); - s->mv[4].y = s->mv[5].y = RSHIFT(mv.y,2); + s->mv[4].x = s->mv[5].x = ROUNDED_RSHIFT(mv.x,2); + s->mv[4].y = s->mv[5].y = ROUNDED_RSHIFT(mv.y,2); } else { s->mv[4] = s->mv[5] = (VP56mv) {mv.x/4, mv.y/4}; } diff --git a/libavutil/common.h b/libavutil/common.h index 8db0291170..0bff7f8f72 100644 --- a/libavutil/common.h +++ b/libavutil/common.h @@ -51,7 +51,7 @@ #endif //rounded division & shift -#define RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b)) +#define ROUNDED_RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b)) /* assume b>0 */ #define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b)) /* Fast a/(1<<b) rounded toward +inf. Assume a>=0 and b>=0 */ -- 2.20.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel