[Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes

[Jan Kiszka]

malc wrote:
> On Sun, 4 May 2008, Jan Kiszka wrote:
> 
>> malc wrote:
>>> On Fri, 2 May 2008, Jan Kiszka wrote:
>>>
>>>> malc wrote:
>>>>> On Fri, 2 May 2008, Jan Kiszka wrote:
>>>>>
>>>>>> Sound though the ALSA driver is skipping here unless I increase the
>>>>>> buffer size. OSS seems to use 16K as well, and 1K was obviously to
>>>>>> small
>>>>>> for recording anyway.
>>>>>>
>>>>>> [ PS: Can someone explain to me why I also have to override the
>>>>>> DAC/ADC_FIXED_FREQ to 48000 to make ALSA work? Suboptimal... ]
>>>>>
>>>>> How exactly it doesn't work if you don't override it? Do you get any
>>>>> messages prefixed with "alsa:"? As for the defaults they were set to
>>>>> 1024/256 because that's what was needed to make it sound on par
>>>>> with OSS
>>>>> on the two machines i had at the time.
> 
> [..snip..]
> 
>>>
>>>
>>> Could you give it a whirl please?
>>
>> No difference - except that it now complains about the 16384 byte buffer
>> size.
> 
> Okay more of the same...
> 
> diff --git a/audio/alsaaudio.c b/audio/alsaaudio.c
> index 43cfa25..59c091d 100644
> --- a/audio/alsaaudio.c
> +++ b/audio/alsaaudio.c
> @@ -428,15 +428,15 @@ static int alsa_open (int in, struct
> alsa_params_req *req,
>                      }
>                  }
> 
> -                err = snd_pcm_hw_params_set_period_size (
> +                err = snd_pcm_hw_params_set_period_size_near (
>                      handle,
>                      hw_params,
> -                    period_size,
> +                    &period_size,
>                      0
>                      );
>                  if (err < 0) {
>                      alsa_logerr2 (err, typ, "Failed to set period size
> %d\n",
> -                                  req->period_size);
> +                                  period_size);
>                      goto err;
>                  }
>              }
> @@ -466,14 +466,14 @@ static int alsa_open (int in, struct
> alsa_params_req *req,
>                  }
>              }
> 
> -            err = snd_pcm_hw_params_set_buffer_size (
> +            err = snd_pcm_hw_params_set_buffer_size_near (
>                  handle,
>                  hw_params,
> -                buffer_size
> +                &buffer_size
>                  );
>              if (err < 0) {
>                  alsa_logerr2 (err, typ, "Failed to set buffer size %d\n",
> -                              req->buffer_size);
> +                              buffer_size);
>                  goto err;
>              }
>          }

Yeah, great, that was the key! Find below the version that works for me
(on 64 bit 8) ). It even obsoletes my buffer size patch. Please merge!

Index: qemu/audio/alsaaudio.c
===================================================================
--- qemu/audio/alsaaudio.c      (Revision 4332)
+++ qemu/audio/alsaaudio.c      (Arbeitskopie)
@@ -396,7 +396,7 @@ static int alsa_open (int in, struct als
         }
         else {
             int dir;
-            snd_pcm_uframes_t minval;
+            snd_pcm_uframes_t minval, val;
 
             if (period_size) {
                 minval = period_size;
@@ -428,15 +428,16 @@ static int alsa_open (int in, struct als
                     }
                 }
 
-                err = snd_pcm_hw_params_set_period_size (
+                val = period_size;
+                err = snd_pcm_hw_params_set_period_size_near (
                     handle,
                     hw_params,
-                    period_size,
+                    &val,
                     0
                     );
                 if (err < 0) {
                     alsa_logerr2 (err, typ, "Failed to set period size %d\n",
-                                  req->period_size);
+                                  period_size);
                     goto err;
                 }
             }
@@ -466,14 +467,15 @@ static int alsa_open (int in, struct als
                 }
             }
 
-            err = snd_pcm_hw_params_set_buffer_size (
+            val = buffer_size;
+            err = snd_pcm_hw_params_set_buffer_size_near (
                 handle,
                 hw_params,
-                buffer_size
+                &val
                 );
             if (err < 0) {
                 alsa_logerr2 (err, typ, "Failed to set buffer size %d\n",
-                              req->buffer_size);
+                              buffer_size);
                 goto err;
             }
         }

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