Change references of Q19.12 to Q4.27 for clarity
Change-Id: I5beb7daf6ff9bc123ff3582f7c294edcaf8652f6
Signed-off-by: Andy Hung <hunga@google.com>
diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index a1783fe..2d67efb 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -1181,7 +1181,7 @@
}
switch (t1.mMixerFormat) {
case AUDIO_FORMAT_PCM_FLOAT:
- memcpy_to_float_from_q19_12(reinterpret_cast<float *>(out), outTemp, BLOCKSIZE * 2);
+ memcpy_to_float_from_q4_27(reinterpret_cast<float *>(out), outTemp, BLOCKSIZE * 2);
out += BLOCKSIZE * 2; // output is 2 floats/frame.
break;
case AUDIO_FORMAT_PCM_16_BIT:
@@ -1274,7 +1274,7 @@
}
switch (t1.mMixerFormat) {
case AUDIO_FORMAT_PCM_FLOAT:
- memcpy_to_float_from_q19_12(reinterpret_cast<float*>(out), outTemp, numFrames*2);
+ memcpy_to_float_from_q4_27(reinterpret_cast<float*>(out), outTemp, numFrames*2);
break;
case AUDIO_FORMAT_PCM_16_BIT:
ditherAndClamp(out, outTemp, numFrames);
@@ -1330,8 +1330,8 @@
in += 2;
int32_t l = mulRL(1, rl, vrl);
int32_t r = mulRL(0, rl, vrl);
- *fout++ = float_from_q19_12(l);
- *fout++ = float_from_q19_12(r);
+ *fout++ = float_from_q4_27(l);
+ *fout++ = float_from_q4_27(r);
// Note: In case of later int16_t sink output,
// conversion and clamping is done by memcpy_to_i16_from_float().
} while (--outFrames);
diff --git a/services/audioflinger/AudioResampler.h b/services/audioflinger/AudioResampler.h
index 0592855..b84567e 100644
--- a/services/audioflinger/AudioResampler.h
+++ b/services/audioflinger/AudioResampler.h
@@ -63,7 +63,7 @@
// A mono provider delivers a sequence of samples.
// A stereo provider delivers a sequence of interleaved pairs of samples.
// Multi-channel providers are not supported.
- // In either case, 'out' holds interleaved pairs of fixed-point signed Q19.12.
+ // In either case, 'out' holds interleaved pairs of fixed-point Q4.27.
// That is, for a mono provider, there is an implicit up-channeling.
// Since this method accumulates, the caller is responsible for clearing 'out' initially.
// FIXME assumes provider is always successful; it should return the actual frame count.
diff --git a/services/audioflinger/RecordTracks.h b/services/audioflinger/RecordTracks.h
index 3ec9889..6fc06d8 100644
--- a/services/audioflinger/RecordTracks.h
+++ b/services/audioflinger/RecordTracks.h
@@ -66,7 +66,7 @@
// updated by RecordThread::readInputParameters_l()
AudioResampler *mResampler;
- // interleaved stereo pairs of fixed-point signed Q19.12
+ // interleaved stereo pairs of fixed-point Q4.27
int32_t *mRsmpOutBuffer;
// current allocated frame count for the above, which may be larger than needed
size_t mRsmpOutFrameCount;
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 65e9eec..feedd89 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -4954,7 +4954,7 @@
// ditherAndClamp() works as long as all buffers returned by
// activeTrack->getNextBuffer() are 32 bit aligned which should be always true.
if (activeTrack->mChannelCount == 1) {
- // temporarily type pun mRsmpOutBuffer from Q19.12 to int16_t
+ // temporarily type pun mRsmpOutBuffer from Q4.27 to int16_t
ditherAndClamp(activeTrack->mRsmpOutBuffer, activeTrack->mRsmpOutBuffer,
framesOut);
// the resampler always outputs stereo samples:
diff --git a/services/audioflinger/test-resample.cpp b/services/audioflinger/test-resample.cpp
index 3ab3ba9..7b7cdac 100644
--- a/services/audioflinger/test-resample.cpp
+++ b/services/audioflinger/test-resample.cpp
@@ -352,8 +352,9 @@
size_t out_frames = output_size/8;
/* set volume precision to 12 bits, so the volume scale is 1<<12.
- * This means the "integer" part fits in the Q19.12 precision
- * representation of output int32_t.
+ * The output int32_t is represented as Q4.27, with 4 bits of guard
+ * followed by the int16_t Q.15 portion, and then 12 trailing bits of
+ * additional precision.
*
* Generally 0 < volumePrecision <= 14 (due to the limits of
* int16_t values for Volume). volumePrecision cannot be 0 due