mpv/filters/f_output_chain.h

#pragma once

#include "options/m_option.h"
#include "video/mp_image.h"

#include "filter.h"

enum mp_output_chain_type {
    MP_OUTPUT_CHAIN_VIDEO = 1,      // --vf
    MP_OUTPUT_CHAIN_AUDIO,          // --af
};

// A classic single-media filter chain, which reflects --vf and --af.
// It manages the user-specified filter chain, and VO/AO output conversions.
// Also handles some automatic filtering (auto rotation and such).
struct mp_output_chain {
    // This filter will have 1 input (from decoder) and 1 output (to VO/AO).
    struct mp_filter *f;

    bool got_output_eof;

    // The filter chain output could not be converted to any format the output
    // supports.
    bool failed_output_conversion;

    // Set if any formats in the chain changed. The user can reset the flag.
    // For implementing change notifications out input/output_params.
    bool reconfig_happened;

    // --- for type==MP_OUTPUT_CHAIN_VIDEO
    struct mp_image_params input_params;
    struct mp_image_params output_params;
    double container_fps;
    void (*update_subtitles)(void *ctx, double pts);
    void *update_subtitles_ctx;

    // --- for type==MP_OUTPUT_CHAIN_AUDIO
    struct mp_aframe *input_aformat;
    struct mp_aframe *output_aformat;
    // If true, there was a format change. output_aformat might have changed,
    // and the implementation drained the filter chain and unset the internal ao
    // reference. The API user needs to call mp_output_chain_set_ao() again.
    // Until this is done, the filter chain will not output new data.
    bool ao_needs_update;
};

// (free by freeing mp_output_chain.f)
struct mp_output_chain *mp_output_chain_create(struct mp_filter *parent,
                                               enum mp_output_chain_type type);

// Set the VO, which will be used to determine basic capabilities like format
// and rotation support, and to init hardware filtering things.
// For type==MP_OUTPUT_CHAIN_VIDEO only.
struct vo;
void mp_output_chain_set_vo(struct mp_output_chain *p, struct vo *vo);

// Set the AO. The AO format will be used to determine the filter chain output.
// The API user may be asked to update the AO midstream if ao_needs_update is
// set.
// For type==MP_OUTPUT_CHAIN_AUDIO only.
struct ao;
void mp_output_chain_set_ao(struct mp_output_chain *p, struct ao *ao);

// Send a command to the filter with the target label.
bool mp_output_chain_command(struct mp_output_chain *p, const char *target,
                             struct mp_filter_command *cmd);

// Perform a seek reset _and_ reset all filter failure states, so that future
// filtering continues normally.
void mp_output_chain_reset_harder(struct mp_output_chain *p);

// Try to exchange the filter list. If creation of any filter fails, roll
// back the changes, and return false.
struct m_obj_settings;
bool mp_output_chain_update_filters(struct mp_output_chain *p,
                                    struct m_obj_settings *list);

// Desired audio speed, with resample being strict resampling.
void mp_output_chain_set_audio_speed(struct mp_output_chain *p,
                                     double speed, double resample, double drop);

// Total delay incurred by the filter chain, as measured by the recent filtered
// frames. The intention is that this sums the measured delays for each filter,
// so if a filter is removed, the caller can estimate how much audio is missing
// due to the change.
// Makes sense for audio only.
double mp_output_get_measured_total_delay(struct mp_output_chain *p);