daniel
71a3b26a47
Docked SWELL window toggled by a new action, drawing the current bank as per-sample min/max thumbnails (PCM_source + peaks) with an in-memory cache. Pure grid-layout/cache-key math in bank_grid (tested). Renames peaks::Sample -> AudioSample to avoid colliding with bank_model::Sample.
70 lines
3.3 KiB
C++
70 lines
3.3 KiB
C++
#pragma once
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// peaks — waveform min/max envelope (thumbnail) computation from raw interleaved
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// PCM. We compute our own thumbnails from the captured file rather than depending
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// on REAPER's peak API: we own the file format, so this is simpler, testable, and
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// dependency-free. A future bank panel (M5) calls this at whatever bin resolution
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// the panel width dictates and draws one min/max envelope per channel.
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//
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// PURE MODULE (CLAUDE.md §load-bearing split): NO REAPER types, NO SWELL, NO
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// vendor/ includes. Standard library only. Builds and unit-tests without REAPER.
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#include <cstddef>
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#include <vector>
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namespace reasampler {
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// Canonical in-memory audio-sample type. `float` is REAPER's native audio buffer
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// format (its render/PCM_source callbacks hand back interleaved 32-bit float), so
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// peaks consumes that directly with no lossy conversion. If a capture ever lands
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// as a different depth, the caller converts to float at the boundary — the
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// thumbnail core stays single-typed.
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//
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// NAMED AudioSample, not `Sample`: `reasampler::Sample` is already bank_model's
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// metadata struct. A `using Sample = float` here would collide at namespace scope
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// wherever both headers are visible (the bank_panel module includes both). The
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// audio-domain name also reads more precisely — this is one PCM sample value.
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using AudioSample = float;
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// One bin of a channel's envelope: the extremes of every sample that fell in it.
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// min <= max always. For an empty bin (more bins than frames), both are 0.
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struct MinMax {
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AudioSample min = 0.0f;
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AudioSample max = 0.0f;
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bool operator==(const MinMax& o) const { return min == o.min && max == o.max; }
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};
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// One channel's envelope: exactly `binCount` bins, in time order.
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using ChannelEnvelope = std::vector<MinMax>;
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// Per-channel envelopes: outer index is channel (channelCount entries, order
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// preserved — never mixed or folded), inner is that channel's bins.
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using Envelope = std::vector<ChannelEnvelope>;
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// Computes a per-channel min/max envelope from interleaved PCM.
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//
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// interleaved frame-interleaved samples: [f0c0, f0c1, ..., f1c0, f1c1, ...].
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// Size must be >= frameCount * channelCount; extra is ignored.
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// channelCount channels per frame (the stride). Each channel is enveloped
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// INDEPENDENTLY — no averaging, no stereo fold (precision
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// invariant: channel count preserved).
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// frameCount frames (samples-per-channel) to consider.
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// binCount requested bins per channel. Honored exactly for any frameCount.
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//
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// Frame->bin partition: frames are split into `binCount` contiguous spans as
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// evenly as possible; when frameCount does not divide evenly, the remainder is
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// spread one-frame-per-bin across the earliest bins (ceil/floor split), so the
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// tail is never dropped and no bin reads out of bounds. When binCount > frameCount
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// the trailing empty bins are {0, 0}.
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//
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// Defined behavior for degenerate input (no UB, no throw):
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// binCount == 0 -> per channel: an empty bin vector.
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// channelCount == 0 -> an empty envelope (no channels).
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// frameCount == 0 -> per channel: binCount bins, all {0, 0}.
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Envelope computeEnvelope(const std::vector<AudioSample>& interleaved,
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std::size_t channelCount,
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std::size_t frameCount,
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std::size_t binCount);
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} // namespace reasampler
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