PCM - Change the hw_params determination order

In snd_pcm_hw_params_choose(), set the buffer size before the period
size and time as default.  This will give more useful configuration for
most of apps, i.e. larger buffer size.

For apps that require the old behavior, now the function checks the
environment variable $LIBASOUND_COMPAT.  If this variable is set to
non-empty, the hw_params is determined in the old way, first period
then buffer sizes.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/src/pcm/pcm_params.c b/src/pcm/pcm_params.c
index 80b3fd21b39db002eacfbb4052199a988d56c850..0e1c3fc506943046fd259f7562bd2d024bfb1956 100644 (file)
--- a/src/pcm/pcm_params.c
+++ b/src/pcm/pcm_params.c
@@ -1081,6 +1081,7 @@ int snd_pcm_hw_param_never_eq(const snd_pcm_hw_params_t *params,
 static int snd_pcm_hw_params_choose(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 {
        int err;
+       const char *compat = getenv("LIBASOUND_COMPAT");
 #ifdef CHOOSE_DEBUG
        snd_output_t *log;
        snd_output_stdio_attach(&log, stderr, 0);
@@ -1103,15 +1104,29 @@ static int snd_pcm_hw_params_choose(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
        err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_RATE, NULL, 0);
        if (err < 0)
                return err;
-       err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_TIME, NULL, 0);
-       if (err < 0)
-               return err;
-       err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_SIZE, NULL, 0);
-       if (err < 0)
-               return err;
-       err = snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_BUFFER_SIZE, NULL, 0);
-       if (err < 0)
-               return err;
+       if (compat && *compat) {
+               /* old mode */
+               err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_TIME, NULL, 0);
+               if (err < 0)
+                       return err;
+               err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_SIZE, NULL, 0);
+               if (err < 0)
+                       return err;
+               err = snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_BUFFER_SIZE, NULL, 0);
+               if (err < 0)
+                       return err;
+       } else {
+               /* determine buffer size first */
+               err = snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_BUFFER_SIZE, NULL, 0);
+               if (err < 0)
+                       return err;
+               err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_SIZE, NULL, 0);
+               if (err < 0)
+                       return err;
+               err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_PERIOD_TIME, NULL, 0);
+               if (err < 0)
+                       return err;
+       }
        err = snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_TICK_TIME, NULL, 0);
        if (err < 0)
                return err;