DVI audio can play 44.1 kHz and 32 kHz sound too

[mikeysklar]

What

DVI audio now plays 32, 44.1 and 48 kHz sound.

Why

Most music files are 44.1 kHz, so they no longer need resampling first.

This matches the rates the Arduino DVI-HSTX library supports.

Builds on #11574, which should merge first. Only the last commit is new here.

Tested

Feather RP2350 (8 MB PSRAM), DVI monitor with speakers, 11.0.0-alpha.1 plus #11574 and this PR.

Test	Result
audioout_rates.py, 1 kHz tone at each rate, twice	All six play, heard on the monitor
audioout_bad_values.py, 22.05 and 96 kHz	ValueError: Invalid sample_rate
board_audio.py	Passes
supervisor.runtime.audio at 44.1, 32, then 48 kHz	All play
Text to speech demo at 48 kHz	Still speaks

Not tested: Fruit Jam, Metro RP2350, other monitors.

Detail
44.1 kHz	Usual N of 6272, CTS rounded
RAM	About 780 bytes more internal RAM while audio is on
Changing rate	The monitor may mute briefly
Idle after 44.1 kHz	Silence keeps being written, since frames never repeat exactly
Not from this PR	audioout_bad_values.py's 720-wide block hits MemoryError on a Feather with DVI forced on; same on #11574

Written with Claude Code. I reviewed the diff, built it, and ran every test above on the board.

🤖 Generated with Claude Code

[tannewt]

I think this needs rebasing/merging now that the dvi audio memory optimizations are merged.

[mikeysklar]

Rebased onto main now that #11574 is merged, so this is down to the one rates commit.

Sorry for the force push.

Retested on a Feather RP2350: 32, 44.1 and 48 kHz. All passed.

• bad values
• supervisor.runtime.audio
• TTS demo

[tannewt]

Sorry for the force push.

NP. Main thing is to avoid it when there are existing inline comments.

[tannewt]

One naming Q. Thanks!

[tannewt]

Does channel_status store more than sample_rate? If not, it'd be clearer to call it that.

[mikeysklar]

It only holds the sample rate code.

hstx_packet_set_audio_samples() now takes sample_rate in Hz, like hstx_packet_set_audio_infoframe(), and looks up the code itself.

Retested on a Feather RP2350 with a DVI monitor. A 1 kHz tone at 48, 44.1 and 32 kHz, twice round, all heard at the same pitch.

rates_show.py

# Plays a 1 kHz tone at each rate and shows the rate on screen.
import array
import math
import time

import audiocore
import board
import displayio
import framebufferio
import picodvi
import terminalio
from adafruit_display_text import label

displayio.release_displays()
fb = picodvi.Framebuffer(
    320, 240,
    clk_dp=board.CKP, clk_dn=board.CKN,
    red_dp=board.D0P, red_dn=board.D0N,
    green_dp=board.D1P, green_dn=board.D1N,
    blue_dp=board.D2P, blue_dn=board.D2N,
    color_depth=8,
)
audio = picodvi.AudioOut(fb)
display = framebufferio.FramebufferDisplay(fb)
text = label.Label(terminalio.FONT, text="wait", color=0xFFFF00, scale=6,
                   anchor_point=(0.5, 0.5), anchored_position=(160, 120))
group = displayio.Group()
group.append(text)
display.root_group = group
time.sleep(3)

for rate in (48000, 44100, 32000, 48000, 44100, 32000):
    length = rate // 100  # Ten periods of 1 kHz.
    tone = audiocore.RawSample(
        array.array("h", [int(math.sin(math.pi * 20 * i / length) * 8000) for i in range(length)]),
        sample_rate=rate,
    )
    text.text = str(rate)
    audio.play(tone, loop=True)
    time.sleep(4)
    print(rate, "playing", audio.playing)
    audio.stop()
    text.text = "-"
    time.sleep(1)
text.text = "done"
print("done")

48000 playing True
44100 playing True
32000 playing True
48000 playing True
44100 playing True
32000 playing True
done