[alsa-devel] [PATCH] alsa-plugins: Pulse: only underrun if no more data has been written

[Raymond Yau]

2011/8/23 Takashi Iwai <tiwai at suse.de>:
 be enough just to have a
> boolean for underrun_detect yes/no.
>
> So, the patch would be like below.
>
> What do you think?
>
>
> Takashi
>
> ---
> diff --git a/pulse/pcm_pulse.c b/pulse/pcm_pulse.c
> index d6c6792..b0e52ab 100644
> --- a/pulse/pcm_pulse.c
> +++ b/pulse/pcm_pulse.c
> @@ -42,6 +42,7 @@ typedef struct snd_pcm_pulse {
>        int handle_underrun;
>
>        size_t offset;
> +       int64_t written;
>
>        pa_stream *stream;
>
> @@ -460,6 +461,7 @@ static snd_pcm_sframes_t pulse_write(snd_pcm_ioplug_t * io,
>
>        /* Make sure the buffer pointer is in sync */
>        pcm->last_size -= writebytes;
> +       pcm->written += writebytes;
>        ret = update_ptr(pcm);
>        if (ret < 0)
>                goto finish;
> @@ -585,6 +587,15 @@ static void stream_request_cb(pa_stream * p, size_t length, void *userdata)
>        update_active(pcm);
>  }
>
> +#if defined(PA_CHECK_VERSION) && PA_CHECK_VERSION(0,99,0)

compile fail at these line since PA_CHECK_VERSION is not defined in
pulseaudio 0.9.14

seem that pcm->wriiten is application pointer of pulse device in bytes

does it mean that pa_stream_get_underflow_index(0 is the hardware pointer ?

does it mean that pulse device no longer can be run 7 x 24 non-stop
since pcm->written may overflow ?

> +#define DEFAULT_HANDLE_UNDERRUN                1
> +#define do_underrun_detect(pcm, p) \
> +       ((pcm)->written <= pa_stream_get_underflow_index(p))
> +#else
> +#define DEFAULT_HANDLE_UNDERRUN                0
> +#define do_underrun_detect(pcm, p)     1       /* always true */
> +#endif
> +
>  static void stream_underrun_cb(pa_stream * p, void *userdata)
>  {
>        snd_pcm_pulse_t *pcm = userdata;
> @@ -594,7 +605,8 @@ static void stream_underrun_cb(pa_stream * p, void *userdata)
>        if (!pcm->p)
>                return;
>
> -       pcm->underrun = 1;
> +       if (do_underrun_detect(pcm, p))
> +               pcm->underrun = 1;
>  }
>
>  static void stream_latency_cb(pa_stream *p, void *userdata) {
> @@ -739,6 +751,7 @@ static int pulse_prepare(snd_pcm_ioplug_t * io)
>
>        pcm->offset = 0;
>        pcm->underrun = 0;
> +       pcm->written = 0;
>
>        /* Reset fake ringbuffer */
>        pcm->last_size = 0;
> @@ -983,7 +996,7 @@ SND_PCM_PLUGIN_DEFINE_FUNC(pulse)
>        const char *server = NULL;
>        const char *device = NULL;
>        const char *fallback_name = NULL;
> -       int handle_underrun = 0;
> +       int handle_underrun = DEFAULT_HANDLE_UNDERRUN;
>        int err;
>        snd_pcm_pulse_t *pcm;
>