From 019a569d42ad9edb531a102e5cd65e83e8eabbf2 Mon Sep 17 00:00:00 2001
From: Vic Lee <llyzs.vic@gmail.com>
Date: Tue, 21 Jun 2016 14:05:29 +0800
Subject: [PATCH] rdpsnd/server: decrease audio latency and make it
 configurable.

---
 channels/rdpsnd/server/rdpsnd_main.c | 21 +++++++++++----------
 include/freerdp/server/rdpsnd.h      |  3 +++
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/channels/rdpsnd/server/rdpsnd_main.c b/channels/rdpsnd/server/rdpsnd_main.c
index 7a93ecd9e..a1d1a2522 100644
--- a/channels/rdpsnd/server/rdpsnd_main.c
+++ b/channels/rdpsnd/server/rdpsnd_main.c
@@ -337,25 +337,26 @@ static UINT rdpsnd_server_select_format(RdpsndServerContext* context, int client
 		goto out;
 	}
 
+	if (context->latency <= 0)
+		context->latency = 50;
+	context->priv->out_frames = context->src_format.nSamplesPerSec * context->latency / 1000;
+	if (context->priv->out_frames < 1)
+		context->priv->out_frames = 1;
 	switch(format->wFormatTag)
 	{
 		case WAVE_FORMAT_DVI_ADPCM:
 			bs = (format->nBlockAlign - 4 * format->nChannels) * 4;
-			context->priv->out_frames = (format->nBlockAlign * 4 * format->nChannels * 2 / bs + 1) * bs / (format->nChannels * 2);
+			context->priv->out_frames -= context->priv->out_frames % bs;
+			if (context->priv->out_frames < bs)
+				context->priv->out_frames = bs;
 			break;
 
 		case WAVE_FORMAT_ADPCM:
 			bs = (format->nBlockAlign - 7 * format->nChannels) * 2 / format->nChannels + 2;
-			context->priv->out_frames = bs * 4;
+			context->priv->out_frames -= context->priv->out_frames % bs;
+			if (context->priv->out_frames < bs)
+				context->priv->out_frames = bs;
 			break;
-		default:
-			context->priv->out_frames = 0x4000 / context->priv->src_bytes_per_frame;
-			break;
-	}
-
-	if (format->nSamplesPerSec != context->src_format.nSamplesPerSec)
-	{
-		context->priv->out_frames = (context->priv->out_frames * context->src_format.nSamplesPerSec + format->nSamplesPerSec - 100) / format->nSamplesPerSec;
 	}
 	context->priv->out_pending_frames = 0;
 
diff --git a/include/freerdp/server/rdpsnd.h b/include/freerdp/server/rdpsnd.h
index 701bca69f..463469ddd 100644
--- a/include/freerdp/server/rdpsnd.h
+++ b/include/freerdp/server/rdpsnd.h
@@ -61,6 +61,9 @@ struct _rdpsnd_server_context
 	/* Server source PCM audio format. Set by server. */
 	AUDIO_FORMAT src_format;
 
+	/* Server audio latency, or buffer size, in milli-seconds. Set by server. */
+	int latency;
+
 	/* Client supported formats. */
 	AUDIO_FORMAT* client_formats;
 	int num_client_formats;