[pulseaudio-discuss] - wrap around when recording output.monitor

Baek Chang baeksan at ccrma.stanford.edu
Wed Sep 15 17:26:59 PDT 2010

looks like in the remap_channels method, calling oil_vectoradd_s16, the
constant to multiply by is set to 1.

                    if (r->map_table[oc][ic] >= 1.0) {
                        static const int16_t one = 1;

                                (int16_t*) dst + oc, o_skip,
                                (int16_t*) dst + oc, o_skip,
                                (int16_t*) src + ic, i_skip,
                                (int) n_frames,
                                &one, &one);


shouldn't there be a divide by 2 somewhere if we are adding two channels

On Wed, Sep 15, 2010 at 2:54 PM, Baek Chang <baeksan at ccrma.stanford.edu>wrote:

> I am seeing warp around happening due to overflow when doing the following.
> parec -r
> --device=alsa_output.pci_8086_269a_sound_card_0_alsa_playback_0.monitor
> output.raw --format=s16le --rate=44100 --channels=1
> paplay --format=s16le --rate=44100 --channels=2
> if i use parec with the same configuration as the sink that I am
> playing the wave file on, then there is no overflow/wraparound.  It
> seems to be a problem with the remapping of the channels from stereo
> to mono.  Is there an additional gain stage applied in this remapping
> that might be causing this?
> I am using pulseaudio 0.9.14
> Thanks
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