diff options
Diffstat (limited to 'libmpv/render.h')
| -rw-r--r-- | libmpv/render.h | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/libmpv/render.h b/libmpv/render.h index ead462cbb6..06811d546c 100644 --- a/libmpv/render.h +++ b/libmpv/render.h @@ -370,9 +370,11 @@ typedef enum mpv_render_param_type { * address 0), the "0" component contains uninitialized garbage (often * the value 0, but not necessarily; the bad naming is inherited from * FFmpeg) + * Pixel alignment size: 4 bytes * "rgb24" * 3 bytes per pixel RGB. This is strongly discouraged because it is * very slow. + * Pixel alignment size: 1 bytes * other * The API may accept other pixel formats, using mpv internal format * names, as long as it's internally marked as RGB, has exactly 1 @@ -390,13 +392,15 @@ typedef enum mpv_render_param_type { * target surface. It must be a multiple of the pixel size, and have space * for the surface width as specified by MPV_RENDER_PARAM_SW_SIZE. * - * It should be a multiple of 64 to facilitate fast SIMD operation. Lower - * alignment might trigger slower code paths. In addition, it appears that - * if libswscale is used, stride must be at least a multiple of 16, or - * libswscale may randomly corrupt memory. The API still accepts unaligned - * values, because libswscale is not supposed to corrupt memory, and whether - * it does depends on its implementation details and bugs. If mpv is built - * with zimg (and zimg is not disabled), no problems should occur. + * Both stride and pointer value should be a multiple of 64 to facilitate + * fast SIMD operation. Lower alignment might trigger slower code paths, + * and in the worst case, will copy the entire target frame. If mpv is built + * with zimg (and zimg is not disabled), the performance impact might be + * less. + * In either cases, the pointer and stride must be aligned at least to the + * pixel alignment size. Otherwise, crashes and undefined behavior is + * possible on platforms which do not support unaligned accesses (either + * through normal memory access or aligned SIMD memory access instructions). */ MPV_RENDER_PARAM_SW_STRIDE = 19, /* @@ -414,8 +418,7 @@ typedef enum mpv_render_param_type { * line (starting at bytepos(w, h) until (pointer + stride * h)) is * writable. * - * It should be a aligned to 64 to facilitate fast SIMD operation. Lower - * alignment might trigger slower code paths. + * See MPV_RENDER_PARAM_SW_STRIDE for alignment requirements. */ MPV_RENDER_PARAM_SW_POINTER = 20, } mpv_render_param_type; |