[alsa-devel] snd_pcm_hw_params_set_buffer_time_near: invalid argument

[Raymond Yau]

2011/3/6 Jean-Yves Avenard <jyavenard at gmail.com>

> Hi there.
>
> I'm a bit puzzled as to what values are considered valids and which
> one aren't when it comes to setting the buffer time with
> snd_pcm_hw_params_set_buffer_time_near.
>
> For example setting a value of 295ms : all ok. From 300ms to 450ms ->
> "Invalid argument".
> but 500ms for example is okay.
>
> What's the logic behind it ?
>

Different sound card driver have different hardware constraints

e.g.  HDA-Intel has the following constraints

    snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
    snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_BYTES,
                   128);
    snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
                   128);

 Attach a program buffertime.c to find out those buffer time with invalid
argument ?
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