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Diffstat (limited to 'filters/f_async_queue.h')
-rw-r--r-- | filters/f_async_queue.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/filters/f_async_queue.h b/filters/f_async_queue.h new file mode 100644 index 0000000000..6b1ffabe36 --- /dev/null +++ b/filters/f_async_queue.h @@ -0,0 +1,92 @@ +#pragma once + +#include "filter.h" + +// A thread safe queue, which buffers a configurable number of frames like a +// FIFO. It's part of the filter framework, and intended to provide such a +// queue between filters. Since a filter graph can't be used from multiple +// threads without synchronization, this provides 2 filters, which are +// implicitly connected. (This seemed much saner than having special thread +// safe mp_pins or such in the filter framework.) +struct mp_async_queue; + +// Create a blank queue. Can be freed with talloc_free(). To use it, you need +// to create input and output filters with mp_async_queue_create_filter(). +// Note that freeing it will only unref it. (E.g. you can free it once you've +// created the input and output filters.) +struct mp_async_queue *mp_async_queue_create(void); + +// Clear all queued data and make the queue "inactive". The latter prevents any +// further communication until mp_async_queue_resume() is called. +// For correct operation, you also need to call reset on the access filters +void mp_async_queue_reset(struct mp_async_queue *queue); + +// Put the queue into "active" mode. If it wasn't, then the consumer is woken +// up (and if there is no data in the queue, this will in turn wake up the +// producer, i.e. start transfers automatically). +void mp_async_queue_resume(struct mp_async_queue *queue); + +// Create a filter to access the queue, and connect it. It's not allowed to +// connect an already connected end of the queue. The filter can be freed at +// any time. +// +// The queue starts out in "inactive" mode, where the queue does not allow +// the producer to write any data. You need to call mp_async_queue_resume() to +// start communication. Actual transfers happen only once the consumer filter +// has read requests on its mp_pin. +// Resetting any of the consumer/producer filters calls mp_async_queue_reset(). +// If the producer filter requested a new frame from its filter graph, and the +// queue is asynchronously set to "inactive", then the requested frame will be +// silently discarded once it reaches the producer filter. +// +// For proper global reset, this order should be preferred: +// - mp_async_queue_reset() +// - reset producer and consumer filters on their respective threads (in any +// order) +// - do whatever other reset work is required +// - mp_async_queue_resume() +// +// parent: filter graph the filter should be part of (or for standalone use, +// create one with mp_filter_create_root()) +// dir: MP_PIN_IN for a filter that writes to the queue, MP_PIN_OUT to read +// queue: queue to attach to (which end of it depends on dir) +// The returned filter will have exactly 1 pin with the requested dir. +struct mp_filter *mp_async_queue_create_filter(struct mp_filter *parent, + enum mp_pin_dir dir, + struct mp_async_queue *queue); + +enum mp_async_queue_sample_unit { + AQUEUE_UNIT_FRAME = 0, // a frame counts as 1 sample + AQUEUE_UNIT_SAMPLES, // number of audio samples (1 for other media types) +}; + +// Setting this struct to all-0 is equivalent to defaults. +struct mp_async_queue_config { + // Maximum size of frames buffered. mp_frame_approx_size() is used. May be + // overshot by up to 1 full frame. Clamped to [1, SIZE_MAX/2]. + int64_t max_bytes; + + // Defines what a "sample" is; affects the fields below. + enum mp_async_queue_sample_unit sample_unit; + + // Maximum number of frames allowed to be buffered at a time (if + // unit!=AQUEUE_UNIT_FRAME, can be overshot by the contents of 1 mp_frame). + // 0 is treated as 1. + int64_t max_samples; + + // Maximum allowed timestamp difference between 2 frames. This still allows + // at least 2 samples. Behavior is unclear on timestamp resets (even if EOF + // frames are between them). A value of 0 disables this completely. + double max_duration; +}; + +// Configure the queue size. By default, the queue size is 1 frame. +// The wakeup_threshold_* fields can be used to avoid too frequent wakeups by +// delaying wakeups, and then making the producer to filter multiple frames at +// once. +// In all cases, the filters can still read/write if the producer/consumer got +// woken up by something else. +// If the current queue contains more frames than the new config allows, the +// queue will remain over-allocated until these frames have been read. +void mp_async_queue_set_config(struct mp_async_queue *queue, + struct mp_async_queue_config cfg); |