AVCSequenceParameterSetReader::readData()

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Performance profile

How much work a call to AVCSequenceParameterSetReader::readData() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Light

Touches nothing outside its own arguments.

Scaling

Scales with input

The body loops, so the work grows with how much data it finds.

Instructions

13–110

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 116.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What one call costs · 13 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost AVCSequenceParameterSetReader::readData() can have, taken from its control-flow graph on PHP 8.5.

Uses · 4

• AVCSequenceParameterSetReader::skipBits()
• AVCSequenceParameterSetReader::getBits()
• AVCSequenceParameterSetReader::expGolombUe()
• AVCSequenceParameterSetReader::expGolombSe()

Source code

View on Trac ↗View on GitHub ↗

784	public function readData() {785		$this->skipBits(8);786		$this->skipBits(8);787		$profile = $this->getBits(8);                               // read profile788		if ($profile > 0) {789			$this->skipBits(8);790			$level_idc = $this->getBits(8);                         // level_idc791			$this->expGolombUe();                                   // seq_parameter_set_id // sps792			$this->expGolombUe();                                   // log2_max_frame_num_minus4793			$picOrderType = $this->expGolombUe();                   // pic_order_cnt_type794			if ($picOrderType == 0) {795				$this->expGolombUe();                               // log2_max_pic_order_cnt_lsb_minus4796			} elseif ($picOrderType == 1) {797				$this->skipBits(1);                                 // delta_pic_order_always_zero_flag798				$this->expGolombSe();                               // offset_for_non_ref_pic799				$this->expGolombSe();                               // offset_for_top_to_bottom_field800				$num_ref_frames_in_pic_order_cnt_cycle = $this->expGolombUe(); // num_ref_frames_in_pic_order_cnt_cycle801				for ($i = 0; $i < $num_ref_frames_in_pic_order_cnt_cycle; $i++) {802					$this->expGolombSe();                           // offset_for_ref_frame[ i ]803				}804			}805			$this->expGolombUe();                                   // num_ref_frames806			$this->skipBits(1);                                     // gaps_in_frame_num_value_allowed_flag807			$pic_width_in_mbs_minus1 = $this->expGolombUe();        // pic_width_in_mbs_minus1808			$pic_height_in_map_units_minus1 = $this->expGolombUe(); // pic_height_in_map_units_minus1809 810			$frame_mbs_only_flag = $this->getBits(1);               // frame_mbs_only_flag811			if ($frame_mbs_only_flag == 0) {812				$this->skipBits(1);                                 // mb_adaptive_frame_field_flag813			}814			$this->skipBits(1);                                     // direct_8x8_inference_flag815			$frame_cropping_flag = $this->getBits(1);               // frame_cropping_flag816 817			$frame_crop_left_offset   = 0;818			$frame_crop_right_offset  = 0;819			$frame_crop_top_offset    = 0;820			$frame_crop_bottom_offset = 0;821 822			if ($frame_cropping_flag) {823				$frame_crop_left_offset   = $this->expGolombUe();   // frame_crop_left_offset824				$frame_crop_right_offset  = $this->expGolombUe();   // frame_crop_right_offset825				$frame_crop_top_offset    = $this->expGolombUe();   // frame_crop_top_offset826				$frame_crop_bottom_offset = $this->expGolombUe();   // frame_crop_bottom_offset827			}828			$this->skipBits(1);                                     // vui_parameters_present_flag829			// etc830 831			$this->width  = (($pic_width_in_mbs_minus1 + 1) * 16) - ($frame_crop_left_offset * 2) - ($frame_crop_right_offset * 2);832			$this->height = ((2 - $frame_mbs_only_flag) * ($pic_height_in_map_units_minus1 + 1) * 16) - ($frame_crop_top_offset * 2) - ($frame_crop_bottom_offset * 2);833		}834	}

Changelog

Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

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