Fix #5019: Added channel up/downmixing code for mono/stereo.

diff --git a/libfreerdp/codec/dsp.c b/libfreerdp/codec/dsp.c
index 4e83791..cfb125e 100644 (file)
--- a/libfreerdp/codec/dsp.c
+++ b/libfreerdp/codec/dsp.c
@@ -111,6 +111,90 @@ struct _FREERDP_DSP_CONTEXT
 #endif
 };
 
+static BOOL freerdp_dsp_channel_mix(FREERDP_DSP_CONTEXT* context,
+                                    const BYTE* src, size_t size,
+                                    const AUDIO_FORMAT* srcFormat,
+                                    const BYTE** data, size_t* length)
+{
+       UINT32 bpp;
+       size_t samples;
+       size_t x, y;
+
+       if (!context || !data || !length)
+               return FALSE;
+
+       if (srcFormat->wFormatTag != WAVE_FORMAT_PCM)
+               return FALSE;
+
+       bpp = srcFormat->wBitsPerSample > 8 ? 2 : 1;
+       samples = size / bpp;
+
+       if (context->format.nChannels == srcFormat->nChannels)
+       {
+               *data = src;
+               *length = size;
+               return TRUE;
+       }
+
+       Stream_SetPosition(context->buffer, 0);
+
+       /* Destination has more channels than source */
+       if (context->format.nChannels > srcFormat->nChannels)
+       {
+               switch (srcFormat->nChannels)
+               {
+                       case 1:
+                               if (!Stream_EnsureCapacity(context->buffer, size * 2))
+                                       return FALSE;
+
+                               for (x = 0; x < samples; x++)
+                               {
+                                       for (y = 0; y < bpp; y++)
+                                               Stream_Write_UINT8(context->buffer, src[x * bpp + y]);
+
+                                       for (y = 0; y < bpp; y++)
+                                               Stream_Write_UINT8(context->buffer, src[x * bpp + y]);
+                               }
+
+                               Stream_SealLength(context->buffer);
+                               *data = Stream_Buffer(context->buffer);
+                               *length = Stream_Length(context->buffer);
+                               return TRUE;
+
+                       case 2: /* We only support stereo, so we can not handle this case. */
+                       default: /* Unsupported number of channels */
+                               return FALSE;
+               }
+       }
+
+       /* Destination has less channels than source */
+       switch (srcFormat->nChannels)
+       {
+               case 2:
+                       if (!Stream_EnsureCapacity(context->buffer, size / 2))
+                               return FALSE;
+
+                       /* Simply drop second channel.
+                        * TODO: Calculate average */
+                       for (x = 0; x < samples; x++)
+                       {
+                               for (y = 0; y < bpp; y++)
+                                       Stream_Write_UINT8(context->buffer, src[2 * x * bpp + y]);
+                       }
+
+                       Stream_SealLength(context->buffer);
+                       *data = Stream_Buffer(context->buffer);
+                       *length = Stream_Length(context->buffer);
+                       return TRUE;
+
+               case 1: /* Invalid, do we want to use a 0 channel sound? */
+               default: /* Unsupported number of channels */
+                       return FALSE;
+       }
+
+       return FALSE;
+}
+
 /**
  * Microsoft Multimedia Standards Update
  * http://download.microsoft.com/download/9/8/6/9863C72A-A3AA-4DDB-B1BA-CA8D17EFD2D4/RIFFNEW.pdf
@@ -1065,11 +1149,19 @@ BOOL freerdp_dsp_encode(FREERDP_DSP_CONTEXT* context, const AUDIO_FORMAT* srcFor
 #if defined(WITH_DSP_FFMPEG)
        return freerdp_dsp_ffmpeg_encode(context, srcFormat, data, length, out);
 #else
+       const BYTE* resampleData;
+       size_t resampleLength;
+       AUDIO_FORMAT format = *srcFormat;
 
        if (!context || !context->encoder || !srcFormat || !data || !out)
                return FALSE;
 
-       if (!freerdp_dsp_resample(context, data, length, srcFormat, &data, &length))
+       if (!freerdp_dsp_channel_mix(context, data, length, srcFormat, &resampleData, &resampleLength))
+               return FALSE;
+
+       format.nChannels = context->format.nChannels;
+
+       if (!freerdp_dsp_resample(context, resampleData, resampleLength, &format, &data, &length))
                return FALSE;
 
        switch (context->format.wFormatTag)