commit 8861338c2a520669a870ee5f3e0c740e438c99bc
author SathishKumar Mani <smani@codeaurora.org> Mon Aug 13 18:40:18 2012 -0700
committer Iliyan Malchev <malchev@google.com> Wed Sep 12 22:45:33 2012 -0700
tree 16959e8103737b10c34b6b438a07078101481ea5
parent 94de74c9450130f9dd01972414b18cb358062876

alsa_sound: add support for low latency playback and recording

b/6865729

- Add deep buffer output in config file
- Configure deep buffer output if flag
  AUDIO_OUTPUT_FLAG_DEEP_BUFFER is set,
  otherwise configure low latency output.
- Add support for low latency recording
- Enable low latency recording path with
  system property
- For 2 buffers and 2048 bytes, reduce
  PLAYBACK_LOW_LATENCY to 21.5 ms

Change-Id: I3c0d54fa473fe89df5a3924de483f16975f4000e
Signed-off-by: Iliyan Malchev <malchev@google.com>

alsa_sound/alsa_default.cpp

diff --git a/alsa_sound/alsa_default.cpp b/alsa_sound/alsa_default.cpp
index 8ff9a0f..0fd9f83 100644
--- a/alsa_sound/alsa_default.cpp
+++ b/alsa_sound/alsa_default.cpp
@@ -625,8 +625,18 @@
     // The PCM stream is opened in blocking mode, per ALSA defaults.  The
     // AudioFlinger seems to assume blocking mode too, so asynchronous mode
     // should not be used.
-    if ((!strcmp(handle->useCase, SND_USE_CASE_VERB_HIFI)) ||
+    if ((!strcmp(handle->useCase, SND_USE_CASE_VERB_HIFI_LOW_POWER)) ||
+        (!strcmp(handle->useCase, SND_USE_CASE_MOD_PLAY_LPA)) ||
+        (!strcmp(handle->useCase, SND_USE_CASE_VERB_HIFI_TUNNEL)) ||
+        (!strcmp(handle->useCase, SND_USE_CASE_MOD_PLAY_TUNNEL))) {
+        ALOGV("LPA/tunnel use case");
+        flags |= PCM_MMAP;
+        flags |= DEBUG_ON;
+    } else if ((!strcmp(handle->useCase, SND_USE_CASE_VERB_HIFI)) ||
+        (!strcmp(handle->useCase, SND_USE_CASE_VERB_HIFI_LOWLATENCY_MUSIC)) ||
+        (!strcmp(handle->useCase, SND_USE_CASE_MOD_PLAY_LOWLATENCY_MUSIC)) ||
         (!strcmp(handle->useCase, SND_USE_CASE_MOD_PLAY_MUSIC))) {
+        ALOGV("Music case");
         flags = PCM_OUT;
     } else {
         flags = PCM_IN;
@@ -1151,6 +1161,8 @@
     ALOGD("use case is %s\n", useCase);
     if (!strncmp(useCase, SND_USE_CASE_VERB_HIFI,
            strlen(SND_USE_CASE_VERB_HIFI)) ||
+        !strncmp(useCase, SND_USE_CASE_VERB_HIFI_LOWLATENCY_MUSIC,
+           strlen(SND_USE_CASE_VERB_HIFI_LOWLATENCY_MUSIC)) ||
         !strncmp(useCase, SND_USE_CASE_VERB_HIFI_LOW_POWER,
             strlen(SND_USE_CASE_VERB_HIFI_LOW_POWER)) ||
         !strncmp(useCase, SND_USE_CASE_VERB_HIFI_TUNNEL,
@@ -1159,6 +1171,8 @@
             strlen(SND_USE_CASE_VERB_DIGITAL_RADIO)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_PLAY_MUSIC,
             strlen(SND_USE_CASE_MOD_PLAY_MUSIC)) ||
+        !strncmp(useCase, SND_USE_CASE_MOD_PLAY_LOWLATENCY_MUSIC,
+            strlen(SND_USE_CASE_MOD_PLAY_LOWLATENCY_MUSIC)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_PLAY_LPA,
             strlen(SND_USE_CASE_MOD_PLAY_LPA)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_PLAY_TUNNEL,
@@ -1168,12 +1182,16 @@
         return USECASE_TYPE_RX;
     } else if (!strncmp(useCase, SND_USE_CASE_VERB_HIFI_REC,
             strlen(SND_USE_CASE_VERB_HIFI_REC)) ||
+        !strncmp(useCase, SND_USE_CASE_VERB_HIFI_LOWLATENCY_REC,
+            strlen(SND_USE_CASE_VERB_HIFI_LOWLATENCY_REC)) ||
         !strncmp(useCase, SND_USE_CASE_VERB_FM_REC,
             strlen(SND_USE_CASE_VERB_FM_REC)) ||
         !strncmp(useCase, SND_USE_CASE_VERB_FM_A2DP_REC,
             strlen(SND_USE_CASE_VERB_FM_A2DP_REC)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_CAPTURE_MUSIC,
             strlen(SND_USE_CASE_MOD_CAPTURE_MUSIC)) ||
+        !strncmp(useCase, SND_USE_CASE_MOD_CAPTURE_LOWLATENCY_MUSIC,
+            strlen(SND_USE_CASE_MOD_CAPTURE_LOWLATENCY_MUSIC)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_CAPTURE_FM,
             strlen(SND_USE_CASE_MOD_CAPTURE_FM)) ||
         !strncmp(useCase, SND_USE_CASE_MOD_CAPTURE_A2DP_FM,