diff options
Diffstat (limited to 'third_party/aom/aom_dsp/pyramid.h')
| -rw-r--r-- | third_party/aom/aom_dsp/pyramid.h | 61 |
1 files changed, 36 insertions, 25 deletions
diff --git a/third_party/aom/aom_dsp/pyramid.h b/third_party/aom/aom_dsp/pyramid.h index 9442a1ff08..745bb7e525 100644 --- a/third_party/aom/aom_dsp/pyramid.h +++ b/third_party/aom/aom_dsp/pyramid.h @@ -19,7 +19,7 @@ #include "config/aom_config.h" #include "aom_scale/yv12config.h" -#include "aom_util/aom_thread.h" +#include "aom_util/aom_pthread.h" #ifdef __cplusplus extern "C" { @@ -57,23 +57,31 @@ typedef struct image_pyramid { // same time // // Semantics: - // * This mutex must be held whenever reading or writing the `valid` flag + // * This mutex must be held whenever reading or writing the + // `filled_levels` field // // * This mutex must also be held while computing the image pyramid, // to ensure that only one thread may do so at a time. // - // * However, once you have read the valid flag and seen a true value, - // it is safe to drop the mutex and read from the remaining fields. - // This is because, once the image pyramid is computed, its contents + // * However, once you have read the filled_levels field and observed + // a value N, it is safe to drop the mutex and read from the remaining + // fields, including the first N pyramid levels (but no higher). + // Note that filled_levels must be read once and cached in a local variable + // in order for this to be safe - it cannot be re-read without retaking + // the mutex. + // + // This works because, once the image pyramid is computed, its contents // will not be changed until the parent frame buffer is recycled, // which will not happen until there are no more outstanding references // to the frame buffer. pthread_mutex_t mutex; #endif - // Flag indicating whether the pyramid contains valid data - bool valid; - // Number of allocated/filled levels in this pyramid - int n_levels; + // Maximum number of levels for the given frame size + // We always allocate enough memory for this many levels, as the memory + // cost of higher levels of the pyramid is minimal. + int max_levels; + // Number of levels which currently hold valid data + int filled_levels; // Pointer to allocated buffer uint8_t *buffer_alloc; // Data for each level @@ -82,11 +90,9 @@ typedef struct image_pyramid { PyramidLayer *layers; } ImagePyramid; -size_t aom_get_pyramid_alloc_size(int width, int height, int n_levels, - bool image_is_16bit); +size_t aom_get_pyramid_alloc_size(int width, int height, bool image_is_16bit); -ImagePyramid *aom_alloc_pyramid(int width, int height, int n_levels, - bool image_is_16bit); +ImagePyramid *aom_alloc_pyramid(int width, int height, bool image_is_16bit); // Fill out a downsampling pyramid for a given frame. // @@ -94,23 +100,28 @@ ImagePyramid *aom_alloc_pyramid(int width, int height, int n_levels, // regardless of the input bit depth. Additional levels are then downscaled // by powers of 2. // -// For small input frames, the number of levels actually constructed -// will be limited so that the smallest image is at least MIN_PYRAMID_SIZE -// pixels along each side. +// This function will ensure that the first `n_levels` levels of the pyramid +// are filled, unless the frame is too small to have this many levels. +// In that case, we will fill all available levels and then stop. // -// However, if the input frame has a side of length < MIN_PYRAMID_SIZE, -// we will still construct the top level. -bool aom_compute_pyramid(const YV12_BUFFER_CONFIG *frame, int bit_depth, - ImagePyramid *pyr); +// Returns the actual number of levels filled, capped at n_levels, +// or -1 on error. +int aom_compute_pyramid(const YV12_BUFFER_CONFIG *frame, int bit_depth, + int n_levels, ImagePyramid *pyr); #ifndef NDEBUG -// Check if a pyramid has already been computed. +// Check if a pyramid has already been computed to at least n levels // This is mostly a debug helper - as it is necessary to hold pyr->mutex -// while reading the valid flag, we cannot just write: -// assert(pyr->valid); +// while reading the number of already-computed levels, we cannot just write: +// assert(pyr->filled_levels >= n_levels); // This function allows the check to be correctly written as: -// assert(aom_is_pyramid_valid(pyr)); -bool aom_is_pyramid_valid(ImagePyramid *pyr); +// assert(aom_is_pyramid_valid(pyr, n_levels)); +// +// Note: This deliberately does not restrict n_levels based on the maximum +// number of permitted levels for the frame size. This allows the check to +// catch cases where the caller forgets to handle the case where +// max_levels is less than the requested number of levels +bool aom_is_pyramid_valid(ImagePyramid *pyr, int n_levels); #endif // Mark a pyramid as no longer containing valid data. |