Remove demo signal generator
Audio capture only — shows NO SIGNAL when libav can't connect. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
rolandnsharp
@@ -66,8 +66,6 @@ proc main() =
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of gsGrid: gsCross
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of gsCross: gsOff
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of gsOff: gsGrid
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of Key.D:
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audio.cyclePreset()
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else:
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discard
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@@ -1,7 +1,6 @@
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## Audio capture via libavdevice/libavformat (dlopen at runtime),
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## with fallback to demo signal.
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## Audio capture via libavdevice/libavformat (dlopen at runtime).
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import osproc, strutils, math
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import osproc, strutils
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import scope
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# ── libav C helper bindings ──────────────────────────────────────────
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@@ -10,8 +9,8 @@ import scope
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{.passL: "-ldl".}
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type
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AVFormatContext = object # opaque, only used as pointer
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AVPacket = object # opaque, only used as pointer
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AVFormatContext = object
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AVPacket = object
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proc av_helper_init(): cint {.importc, cdecl.}
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proc av_helper_open_pulse(ctx: ptr ptr AVFormatContext,
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@@ -46,102 +45,62 @@ proc findMonitorSource(): string =
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except: discard
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""
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# ── Audio capture types ──────────────────────────────────────────────
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# ── Audio capture ────────────────────────────────────────────────────
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type
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AudioMode* = enum
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amLive ## Direct libav capture
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amDemo ## Built-in synthesized waveforms
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AudioCapture* = object
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mode*: AudioMode
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fmtCtx: ptr AVFormatContext
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packet: ptr AVPacket
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streamIdx: cint
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phase: float
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demoFreqL*, demoFreqR*: float
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demoPreset*: int
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# ── Start / stop ─────────────────────────────────────────────────────
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live*: bool
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proc startAudio*(): AudioCapture =
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let monitor = findMonitorSource()
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if monitor.len > 0:
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block libav:
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if av_helper_init() < 0: break libav
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if monitor.len == 0: return
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if av_helper_init() < 0: return
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var ctx: ptr AVFormatContext = nil
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if av_helper_open_pulse(addr ctx, monitor.cstring) < 0: break libav
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if av_helper_open_pulse(addr ctx, monitor.cstring) < 0: return
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if av_helper_find_stream_info(ctx) < 0:
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av_helper_close(addr ctx)
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break libav
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return
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let idx = av_helper_find_audio_stream(ctx)
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let pkt = av_helper_packet_alloc()
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if pkt != nil:
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return AudioCapture(
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mode: amLive, fmtCtx: ctx, packet: pkt,
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streamIdx: idx.cint,
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demoFreqL: 440.0, demoFreqR: 330.0)
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if pkt == nil:
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av_helper_close(addr ctx)
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return
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AudioCapture(mode: amDemo, demoFreqL: 440.0, demoFreqR: 330.0)
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AudioCapture(fmtCtx: ctx, packet: pkt, streamIdx: idx.cint, live: true)
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proc stop*(cap: var AudioCapture) =
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if cap.mode == amLive:
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if cap.live:
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if cap.packet != nil: av_helper_packet_free(addr cap.packet)
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if cap.fmtCtx != nil: av_helper_close(addr cap.fmtCtx)
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proc sourceLabel*(cap: AudioCapture): string =
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if cap.mode == amLive: "LIVE" else: "DEMO"
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# ── Preset cycling ───────────────────────────────────────────────────
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proc cyclePreset*(cap: var AudioCapture) =
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if cap.mode != amDemo: return
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cap.demoPreset = (cap.demoPreset + 1) mod 4
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case cap.demoPreset
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of 0: cap.demoFreqL = 440.0; cap.demoFreqR = 330.0 # 4:3
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of 1: cap.demoFreqL = 440.0; cap.demoFreqR = 440.0 # 1:1
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of 2: cap.demoFreqL = 440.0; cap.demoFreqR = 220.0 # 2:1
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of 3: cap.demoFreqL = 440.0; cap.demoFreqR = 293.3 # 3:2
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else: discard
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# ── Sample reading ───────────────────────────────────────────────────
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if cap.live: "LIVE" else: "NO SIGNAL"
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proc readSamples*(cap: var AudioCapture, scope: var Scope) =
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case cap.mode
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of amLive:
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if not cap.live: return
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const frameSize = 4 # 2ch × 16-bit
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var totalSamples = 0
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while totalSamples < scope.samplesL.len:
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var total = 0
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while total < scope.samplesL.len:
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let ret = av_helper_read_frame(cap.fmtCtx, cap.packet)
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if ret < 0: break
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if av_helper_packet_stream(cap.packet) == cap.streamIdx:
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let data = av_helper_packet_data(cap.packet)
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let size = av_helper_packet_size(cap.packet)
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let frames = size div frameSize
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for i in 0..<frames:
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if totalSamples >= scope.samplesL.len: break
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for i in 0..<(size div frameSize):
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if total >= scope.samplesL.len: break
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let off = i * frameSize
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let left = cast[int16]((data[off + 1].uint16 shl 8) or data[off].uint16)
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let right = cast[int16]((data[off + 3].uint16 shl 8) or data[off + 2].uint16)
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scope.samplesL[totalSamples] = left.float / 32768.0
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scope.samplesR[totalSamples] = right.float / 32768.0
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totalSamples += 1
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scope.samplesL[total] = left.float / 32768.0
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scope.samplesR[total] = right.float / 32768.0
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total += 1
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av_helper_packet_unref(cap.packet)
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if totalSamples > 0: break
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scope.sampleCount = totalSamples
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of amDemo:
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scope.sampleCount = scope.samplesL.len
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let cycles = 3.0 / scope.timeDiv
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let drift = sin(cap.phase * 0.3) * 0.1
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let rL = cap.demoFreqL / 440.0
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let rR = cap.demoFreqR / 440.0
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for i in 0..<scope.sampleCount:
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let t = cap.phase + (i.float / scope.sampleCount.float) * cycles * 2.0 * PI
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scope.samplesL[i] = sin(t * rL) * 0.7 +
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sin(t * rL * 2.0) * 0.15 +
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sin(t * rL * 3.0 + drift) * 0.08
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scope.samplesR[i] = sin(t * rR + 0.5) * 0.7 +
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sin(t * rR * 2.0 + 0.3) * 0.2
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cap.phase += 0.05
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if total > 0: break
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scope.sampleCount = total
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