<html><head></head><body>I don't see how it reduces latency, no. Audio latency is largely bound by the packet/period size, not by exclusive mode.<br><br><div class="gmail_quote">Le 25 octobre 2019 10:17:21 GMT+03:00, Thomas Guillem <thomas@gllm.fr> a écrit :<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail"><br><br>On Thu, Oct 24, 2019, at 20:55, Rémi Denis-Courmont wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;">Le torstaina 24. lokakuuta 2019, 15.37.13 EEST Thomas Guillem a écrit :<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;">cf. WASAPI_EXCLUSIVE_LONGTEXT<hr> modules/audio_output/wasapi.c | 174 +++++++++++++++++++++++++++++++++-<br> 1 file changed, 170 insertions(+), 4 deletions(-)<br><br>diff --git a/modules/audio_output/wasapi.c b/modules/audio_output/wasapi.c<br>index daa946f8afc..91defb250fb 100644<br>--- a/modules/audio_output/wasapi.c<br>+++ b/modules/audio_output/wasapi.c<br>@@ -588,6 +588,154 @@ static void Stop(aout_stream_t *s)<br> free(sys);<br> }<br><br>+/*<br>+ * This function will try to find the closest PCM format that is accepted<br>by + * the sound card. Exclusive here means a direct access to the sound<br>card. The + * format arguments and the return code of this function behave<br>exactly like + * IAudioClient_IsFormatSupported().<br>+ */<br>+static HRESULT GetExclusivePCMFormat(IAudioClient *c, const WAVEFORMATEX<br>*pwf, + WAVEFORMATEX **ppwf_closest) +{<br>+ HRESULT hr;<br>+ const AUDCLNT_SHAREMODE exclusive = AUDCLNT_SHAREMODE_EXCLUSIVE;<br>+<br>+ *ppwf_closest = NULL;<br>+<br>+ /* First try the input format */<br>+ hr = IAudioClient_IsFormatSupported(c, exclusive, pwf, NULL);<br>+<br>+ if (hr != AUDCLNT_E_UNSUPPORTED_FORMAT)<br>+ {<br>+ assert(hr != S_FALSE); /* S_FALSE reserved for shared mode */<br>+ return hr;<br>+ }<br>+<br>+ /* This format come from vlc_ToWave() */<br>+ assert(pwf->wFormatTag == WAVE_FORMAT_EXTENSIBLE);<br>+ const WAVEFORMATEXTENSIBLE *pwfe = (void *) pwf;<br>+ assert(IsEqualIID(&pwfe->SubFormat, &KSDATAFORMAT_SUBTYPE_IEEE_FLOAT)<br>+ || IsEqualIID(&pwfe->SubFormat, &KSDATAFORMAT_SUBTYPE_PCM));<br>+<br>+ /* Allocate the output closest format */<br>+ WAVEFORMATEXTENSIBLE *pwfe_closest =<br>+ CoTaskMemAlloc(sizeof(WAVEFORMATEXTENSIBLE));<br>+ if (!pwfe_closest)<br>+ return E_FAIL;<br>+ WAVEFORMATEX *pwf_closest = &pwfe_closest->Format;<br>+<br>+ /* Setup the fallback arrays. There are 3 properties to check: the<br>format, + * the samplerate and the channels. There are maximum of 4<br>formats to + * check, 3 samplerates, and 2 channels configuration. So,<br>that is a + * maximum of 4x3x2=24 checks */<br>+<br>+ /* The format fallback order is dependent of the input format. We don't<br>+ * want to use a high quality format when it's not needed but we<br>prefer to + * use a high quality format instead of a lower one */<br>+ static const uint16_t bits_pcm8_fallback[] = { 8, 16, 24, 32 };<br>+ static const uint16_t bits_pcm16_fallback[] = { 16, 24, 32, 8 };<br>+ static const uint16_t bits_pcm24_fallback[] = { 24, 32, 16, 8 };<br>+ static const uint16_t bits_pcm32_fallback[] = { 32, 24, 16, 8 };<br>+<br>+ static const size_t bits_fallback_size =<br>ARRAY_SIZE(bits_pcm8_fallback); +<br>+ const uint16_t *bits_fallback;<br>+ switch (pwf->wBitsPerSample)<br>+ {<br>+ case 64: /* fall through */<br>+ case 32: bits_fallback = bits_pcm32_fallback; break;<br>+ case 24: bits_fallback = bits_pcm24_fallback; break;<br>+ case 16: bits_fallback = bits_pcm16_fallback; break;<br>+ case 8: bits_fallback = bits_pcm8_fallback; break;<br>+ default: vlc_assert_unreachable();<br>+ }<br>+<br>+ /* Check the input samplerate, then 48kHz and 44.1khz */<br>+ const uint32_t samplerate_fallback[] = {<br>+ pwf->nSamplesPerSec,<br>+ pwf->nSamplesPerSec == 48000 ? 0 : 48000,<br>+ pwf->nSamplesPerSec == 44100 ? 0 : 44100,<br>+ };<br>+ const size_t samplerate_fallback_size =<br>ARRAY_SIZE(samplerate_fallback); +<br>+ /* Check the input number of channels, then stereo */<br>+ const uint16_t channels_fallback[] = {<br>+ pwf->nChannels,<br>+ pwf->nChannels == 2 ? 0 : 2,<br>+ };<br>+ const size_t channels_fallback_size = ARRAY_SIZE(channels_fallback);<br></blockquote>Really the only point in exclusive mode is bit exact. If you need to convert, <br>there is really no point, especially if the sample rate and/or the channel <br>mappings differ. This is waaaaay needlessly complicated.<br></blockquote><br>An other point of exclusive is to reduce the audio latency.<br><br>> <br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;">-- <br>レミ・デニ-クールモン<br><a href="http://www.remlab.net/">http://www.remlab.net/</a><hr>vlc-devel mailing list<br>To unsubscribe or modify your subscription options:<br><a href="https://mailman.videolan.org/listinfo/vlc-devel">https://mailman.videolan.org/listinfo/vlc-devel</a><br></blockquote><hr>vlc-devel mailing list<br>To unsubscribe or modify your subscription options:<br><a href="https://mailman.videolan.org/listinfo/vlc-devel">https://mailman.videolan.org/listinfo/vlc-devel</a></pre></blockquote></div><br>-- <br>Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser ma brièveté.</body></html>