Fix: Audio not playing on Windows

[RobinDadswell]

This may also fix issues on other devices, however this is not confirmed as I do not have alternative Operating Systems to check on

It also allows for changing the audio device to output through without needing to restart the whole application

[RobinDadswell]

Fixes #19
possibly fixes #33

[RobinDadswell]

@teancom @marcelveldt can I get a review of this one as it's a major issue for users

[Jesstr8803]

Tested on Windows 11 with a TOPPING USB DAC and ran into a hi-res-DAC edge case the current fix doesn't cover. Posting in case it's useful.

👋 Heads up: I'm not a Rust dev — I used Claude Code to clone the fork, build, debug the stderr output, and write the patch below. So I can answer questions about the symptoms / what I tested, but for deep questions about the diff itself you may want to verify it independently.

Repro: DAC default format set to 384000 Hz / 24-bit in Windows Sound → Properties → Advanced (common for audiophile DACs). With the patch applied, audio still doesn't play.

Diagnostic from stderr:

[Sendspin] Using default output device: Speakers (TOPPING USB DAC)
[Sendspin] No reliable device format capabilities found; using conservative fallback formats: 2ch/48000Hz/16bit, 2ch/44100Hz/16bit
[Sendspin] StreamStart format from server: codec=pcm, channels=2, sample_rate=48000, bit_depth=16
[Sendspin] Failed to create SyncedPlayer for channels=2, sample_rate=48000, bit_depth=16: Audio output error: The requested stream configuration is not supported by the device.
Root cause:

On Windows shared-mode WASAPI, cpal::Device::supported_output_configs() returns only configs at the device's currently configured shared-mode rate. For my DAC that's [ch=2, rate=384000..384000Hz, fmt={U8|I16|I32|F32}]. The current derive_supported_pcm_formats checks [48000, 44100, 96000] against that range, all fail (rate < min_rate), the function returns empty, and fallback_supported_formats() (48k/44.1k 16-bit) is advertised — which the device then rejects when cpal tries to open the stream at 48k against a 384k mix format.

Workaround for users hitting this: change Windows default format to 48000 Hz. But that defeats the point of a hi-res DAC.

Suggested fix:

Anchor on device.default_output_config() so the device's native rate is always advertised, and add common rates only when supported_output_configs() actually covers them. Full replacement function I've been running locally:

pub fn derive_supported_pcm_formats(device: Option<&cpal::Device>) -> Vec {
let Some(device) = device else {
return vec![];
};

let default_cfg = device.default_output_config().ok();
let native_rate = default_cfg.as_ref().map(|c| c.sample_rate().0);
let native_supports_24bit = default_cfg
    .as_ref()
    .map(|c| {
        let s = format!("{:?}", c.sample_format());
        s.contains("I24") || s.contains("I32") || s.contains("F32")
    })
    .unwrap_or(false);

let mut collected = BTreeSet::new();

// Always include the device's native rate so negotiation succeeds on
// Windows shared-mode WASAPI.
if let Some(rate) = native_rate {
    collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 16 });
    if native_supports_24bit {
        collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 24 });
    }
}

// Add common rates only when supported_output_configs explicitly covers them.
if let Ok(configs) = device.supported_output_configs() {
    let common_rates = [48_000u32, 44_100u32, 96_000u32];
    for cfg in configs {
        if cfg.channels() < 2 {
            continue;
        }
        let min_rate = cfg.min_sample_rate().0;
        let max_rate = cfg.max_sample_rate().0;
        let supports_24bit = format!("{:?}", cfg.sample_format()).contains("I24");

        for rate in common_rates {
            if rate < min_rate || rate > max_rate {
                continue;
            }
            collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 16 });
            if supports_24bit {
                collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 24 });
            }
        }
    }
}

let mut result: Vec<_> = collected.into_iter().collect();
result.sort_by_key(|f| {
    let rate_rank = if Some(f.sample_rate) == native_rate {
        0
    } else {
        match f.sample_rate {
            48_000 => 1,
            44_100 => 2,
            96_000 => 3,
            _ => 4,
        }
    };
    let depth_rank = i32::from(f.bit_depth != 16);
    (rate_rank, depth_rank, f.sample_rate, f.bit_depth)
});
result

}
Verified locally: with this patch the DAC plays at native 384kHz without changing Windows sound settings.

[teancom]

This looks lovely, thank you! A few things to tweak but I think this will be a great change.

[RobinDadswell]

Tested on Windows 11 with a TOPPING USB DAC and ran into a hi-res-DAC edge case the current fix doesn't cover. Posting in case it's useful.

👋 Heads up: I'm not a Rust dev — I used Claude Code to clone the fork, build, debug the stderr output, and write the patch below. So I can answer questions about the symptoms / what I tested, but for deep questions about the diff itself you may want to verify it independently.

Repro: DAC default format set to 384000 Hz / 24-bit in Windows Sound → Properties → Advanced (common for audiophile DACs). With the patch applied, audio still doesn't play.

Diagnostic from stderr:

[Sendspin] Using default output device: Speakers (TOPPING USB DAC) [Sendspin] No reliable device format capabilities found; using conservative fallback formats: 2ch/48000Hz/16bit, 2ch/44100Hz/16bit [Sendspin] StreamStart format from server: codec=pcm, channels=2, sample_rate=48000, bit_depth=16 [Sendspin] Failed to create SyncedPlayer for channels=2, sample_rate=48000, bit_depth=16: Audio output error: The requested stream configuration is not supported by the device. Root cause:

On Windows shared-mode WASAPI, cpal::Device::supported_output_configs() returns only configs at the device's currently configured shared-mode rate. For my DAC that's [ch=2, rate=384000..384000Hz, fmt={U8|I16|I32|F32}]. The current derive_supported_pcm_formats checks [48000, 44100, 96000] against that range, all fail (rate < min_rate), the function returns empty, and fallback_supported_formats() (48k/44.1k 16-bit) is advertised — which the device then rejects when cpal tries to open the stream at 48k against a 384k mix format.

Workaround for users hitting this: change Windows default format to 48000 Hz. But that defeats the point of a hi-res DAC.

Suggested fix:

Anchor on device.default_output_config() so the device's native rate is always advertised, and add common rates only when supported_output_configs() actually covers them. Full replacement function I've been running locally:

pub fn derive_supported_pcm_formats(device: Option<&cpal::Device>) -> Vec { let Some(device) = device else { return vec![]; };

let default_cfg = device.default_output_config().ok();
let native_rate = default_cfg.as_ref().map(|c| c.sample_rate().0);
let native_supports_24bit = default_cfg
    .as_ref()
    .map(|c| {
        let s = format!("{:?}", c.sample_format());
        s.contains("I24") || s.contains("I32") || s.contains("F32")
    })
    .unwrap_or(false);

let mut collected = BTreeSet::new();

// Always include the device's native rate so negotiation succeeds on
// Windows shared-mode WASAPI.
if let Some(rate) = native_rate {
    collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 16 });
    if native_supports_24bit {
        collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 24 });
    }
}

// Add common rates only when supported_output_configs explicitly covers them.
if let Ok(configs) = device.supported_output_configs() {
    let common_rates = [48_000u32, 44_100u32, 96_000u32];
    for cfg in configs {
        if cfg.channels() < 2 {
            continue;
        }
        let min_rate = cfg.min_sample_rate().0;
        let max_rate = cfg.max_sample_rate().0;
        let supports_24bit = format!("{:?}", cfg.sample_format()).contains("I24");

        for rate in common_rates {
            if rate < min_rate || rate > max_rate {
                continue;
            }
            collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 16 });
            if supports_24bit {
                collected.insert(SupportedPcmFormat { channels: 2, sample_rate: rate, bit_depth: 24 });
            }
        }
    }
}

let mut result: Vec<_> = collected.into_iter().collect();
result.sort_by_key(|f| {
    let rate_rank = if Some(f.sample_rate) == native_rate {
        0
    } else {
        match f.sample_rate {
            48_000 => 1,
            44_100 => 2,
            96_000 => 3,
            _ => 4,
        }
    };
    let depth_rank = i32::from(f.bit_depth != 16);
    (rate_rank, depth_rank, f.sample_rate, f.bit_depth)
});
result

} Verified locally: with this patch the DAC plays at native 384kHz without changing Windows sound settings.

can you have a pull of the latest version and see if it works for you now please :D

[teancom]

One final tweak and we're good to go!

[Jesstr8803]

@RobinDadswell Confirmed working at 384kHz on the TOPPING USB DAC with the latest commit — no Windows audio config changes needed. 🎉

Thanks for the quick turnaround on the fix!

[teancom]

Thanks, @RobinDadswell !