Hi Volker,
> To hear this,
> start QEMU with qemu-system-x86_64 -machine pcspk-audiodev=audio0
> -device ich9-intel-hda -device hda-duplex,audiodev=audio0 -audiodev
> pipewire,id=audio0,out.mixing-engine=off ...
>
I hear the clipped audio stream with these options. IMO, I don't think
memset is responsible for that behaviour, I still hear the harsh sound with
"-audiodev pa". I also tried using an alternative like:
@@ -117,7 +118,7 @@ playback_on_process(void *data)
}
if (avail == 0) {
- memset(p, 0, n_bytes);
+ p = g_malloc0(sizeof(n_bytes));
} else {
The clipped audio issue is still persistent.
Thanks,
Dorinda.
On Sun, Mar 12, 2023 at 9:01 AM Volker Rümelin <vr_q...@t-online.de> wrote:
> > +/* output data processing function to read stuffs from the buffer */
> > +static void
> > +playback_on_process(void *data)
> > +{
> > + PWVoice *v = (PWVoice *) data;
> > + void *p;
> > + struct pw_buffer *b;
> > + struct spa_buffer *buf;
> > + uint32_t n_frames, req, index, n_bytes;
> > + int32_t avail;
> > +
> > + if (!v->stream) {
> > + return;
> > + }
> > +
> > + /* obtain a buffer to read from */
> > + b = pw_stream_dequeue_buffer(v->stream);
> > + if (b == NULL) {
> > + error_report("out of buffers: %s", strerror(errno));
> > + return;
> > + }
> > +
> > + buf = b->buffer;
> > + p = buf->datas[0].data;
> > + if (p == NULL) {
> > + return;
> > + }
> > + req = b->requested * v->frame_size;
> > + if (req == 0) {
> > + req = 4096 * v->frame_size;
> > + }
> > + n_frames = SPA_MIN(req, buf->datas[0].maxsize);
> > + n_bytes = n_frames * v->frame_size;
> > +
> > + /* get no of available bytes to read data from buffer */
> > +
> > + avail = spa_ringbuffer_get_read_index(&v->ring, &index);
> > +
> > + if (!v->enabled) {
> > + avail = 0;
> > + }
> > +
> > + if (avail == 0) {
> > + memset(p, 0, n_bytes);
>
> memset() doesn't work for unsigned samples. For unsigned samples, a
> stream of zeros is silence with a DC offset. When Pipewire mixes this
> stream with another, the result is a clipped audio stream. To hear this,
> start QEMU with qemu-system-x86_64 -machine pcspk-audiodev=audio0
> -device ich9-intel-hda -device hda-duplex,audiodev=audio0 -audiodev
> pipewire,id=audio0,out.mixing-engine=off ... and start playback with the
> hda device.
>
> With best regards,
> Volker
>
> > + } else {
> > + if (avail < (int32_t) n_bytes) {
> > + n_bytes = avail;
> > + }
> > +
> > + spa_ringbuffer_read_data(&v->ring,
> > + v->buffer, RINGBUFFER_SIZE,
> > + index & RINGBUFFER_MASK, p,
> n_bytes);
> > +
> > + index += n_bytes;
> > + spa_ringbuffer_read_update(&v->ring, index);
> > + }
> > +
> > + buf->datas[0].chunk->offset = 0;
> > + buf->datas[0].chunk->stride = v->frame_size;
> > + buf->datas[0].chunk->size = n_bytes;
> > +
> > + /* queue the buffer for playback */
> > + pw_stream_queue_buffer(v->stream, b);
> > +}
> > +
> >
>
>
