From b64af9a221c1df4853ab7c7766d5f956c61b8765 Mon Sep 17 00:00:00 2001
From: Andreas Huber <andih@google.com>
Date: Wed, 23 Jun 2010 11:11:58 -0700
Subject: [PATCH] Fix a number of timestamp mismatches in the mp3 extractor and
 decoder that would lead to invalid reporting of the current playback time for
 mono and/or non-44100 kHz mp3s.

Change-Id: I11abc05b62a958ffbc99ca997cd184a2f2199352
related-to-bug: 2667479
---
 media/libstagefright/MP3Extractor.cpp         |  5 +-
 .../codecs/mp3dec/MP3Decoder.cpp              | 57 ++++++++++---------
 media/libstagefright/include/MP3Decoder.h     |  7 ++-
 3 files changed, 39 insertions(+), 30 deletions(-)

diff --git a/media/libstagefright/MP3Extractor.cpp b/media/libstagefright/MP3Extractor.cpp
index f9251e1c8f446..69c3a72f55703 100644
--- a/media/libstagefright/MP3Extractor.cpp
+++ b/media/libstagefright/MP3Extractor.cpp
@@ -634,6 +634,7 @@ status_t MP3Source::read(
     }
 
     size_t frame_size;
+    int bitrate;
     for (;;) {
         ssize_t n = mDataSource->readAt(mCurrentPos, buffer->data(), 4);
         if (n < 4) {
@@ -646,7 +647,7 @@ status_t MP3Source::read(
         uint32_t header = U32_AT((const uint8_t *)buffer->data());
 
         if ((header & kMask) == (mFixedHeader & kMask)
-            && get_mp3_frame_size(header, &frame_size)) {
+            && get_mp3_frame_size(header, &frame_size, NULL, NULL, &bitrate)) {
             break;
         }
 
@@ -683,7 +684,7 @@ status_t MP3Source::read(
     buffer->meta_data()->setInt64(kKeyTime, mCurrentTimeUs);
 
     mCurrentPos += frame_size;
-    mCurrentTimeUs += 1152 * 1000000 / 44100;
+    mCurrentTimeUs += frame_size * 8000ll / bitrate;
 
     *out = buffer;
 
diff --git a/media/libstagefright/codecs/mp3dec/MP3Decoder.cpp b/media/libstagefright/codecs/mp3dec/MP3Decoder.cpp
index efcb4764c5538..f40bd11f1e222 100644
--- a/media/libstagefright/codecs/mp3dec/MP3Decoder.cpp
+++ b/media/libstagefright/codecs/mp3dec/MP3Decoder.cpp
@@ -27,13 +27,35 @@ namespace android {
 
 MP3Decoder::MP3Decoder(const sp<MediaSource> &source)
     : mSource(source),
+      mNumChannels(0),
       mStarted(false),
       mBufferGroup(NULL),
       mConfig(new tPVMP3DecoderExternal),
       mDecoderBuf(NULL),
       mAnchorTimeUs(0),
-      mNumSamplesOutput(0),
+      mNumFramesOutput(0),
       mInputBuffer(NULL) {
+    init();
+}
+
+void MP3Decoder::init() {
+    sp<MetaData> srcFormat = mSource->getFormat();
+
+    int32_t sampleRate;
+    CHECK(srcFormat->findInt32(kKeyChannelCount, &mNumChannels));
+    CHECK(srcFormat->findInt32(kKeySampleRate, &sampleRate));
+
+    mMeta = new MetaData;
+    mMeta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_RAW);
+    mMeta->setInt32(kKeyChannelCount, mNumChannels);
+    mMeta->setInt32(kKeySampleRate, sampleRate);
+
+    int64_t durationUs;
+    if (srcFormat->findInt64(kKeyDuration, &durationUs)) {
+        mMeta->setInt64(kKeyDuration, durationUs);
+    }
+
+    mMeta->setCString(kKeyDecoderComponent, "MP3Decoder");
 }
 
 MP3Decoder::~MP3Decoder() {
@@ -62,7 +84,7 @@ status_t MP3Decoder::start(MetaData *params) {
     mSource->start();
 
     mAnchorTimeUs = 0;
-    mNumSamplesOutput = 0;
+    mNumFramesOutput = 0;
     mStarted = true;
 
     return OK;
@@ -90,26 +112,7 @@ status_t MP3Decoder::stop() {
 }
 
 sp<MetaData> MP3Decoder::getFormat() {
-    sp<MetaData> srcFormat = mSource->getFormat();
-
-    int32_t numChannels;
-    int32_t sampleRate;
-    CHECK(srcFormat->findInt32(kKeyChannelCount, &numChannels));
-    CHECK(srcFormat->findInt32(kKeySampleRate, &sampleRate));
-
-    sp<MetaData> meta = new MetaData;
-    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_RAW);
-    meta->setInt32(kKeyChannelCount, numChannels);
-    meta->setInt32(kKeySampleRate, sampleRate);
-
-    int64_t durationUs;
-    if (srcFormat->findInt64(kKeyDuration, &durationUs)) {
-        meta->setInt64(kKeyDuration, durationUs);
-    }
-
-    meta->setCString(kKeyDecoderComponent, "MP3Decoder");
-
-    return meta;
+    return mMeta;
 }
 
 status_t MP3Decoder::read(
@@ -122,7 +125,7 @@ status_t MP3Decoder::read(
     if (options && options->getSeekTo(&seekTimeUs)) {
         CHECK(seekTimeUs >= 0);
 
-        mNumSamplesOutput = 0;
+        mNumFramesOutput = 0;
 
         if (mInputBuffer) {
             mInputBuffer->release();
@@ -142,7 +145,7 @@ status_t MP3Decoder::read(
         int64_t timeUs;
         if (mInputBuffer->meta_data()->findInt64(kKeyTime, &timeUs)) {
             mAnchorTimeUs = timeUs;
-            mNumSamplesOutput = 0;
+            mNumFramesOutput = 0;
         } else {
             // We must have a new timestamp after seeking.
             CHECK(seekTimeUs < 0);
@@ -179,7 +182,7 @@ status_t MP3Decoder::read(
 
         // This is recoverable, just ignore the current frame and
         // play silence instead.
-        memset(buffer->data(), 0, mConfig->outputFrameSize);
+        memset(buffer->data(), 0, mConfig->outputFrameSize * sizeof(int16_t));
         mConfig->inputBufferUsedLength = mInputBuffer->range_length();
     }
 
@@ -198,9 +201,9 @@ status_t MP3Decoder::read(
     buffer->meta_data()->setInt64(
             kKeyTime,
             mAnchorTimeUs
-                + (mNumSamplesOutput * 1000000) / mConfig->samplingRate);
+                + (mNumFramesOutput * 1000000) / mConfig->samplingRate);
 
-    mNumSamplesOutput += mConfig->outputFrameSize / sizeof(int16_t);
+    mNumFramesOutput += mConfig->outputFrameSize / mNumChannels;
 
     *out = buffer;
 
diff --git a/media/libstagefright/include/MP3Decoder.h b/media/libstagefright/include/MP3Decoder.h
index 88aa4c602d61d..4086fb603b539 100644
--- a/media/libstagefright/include/MP3Decoder.h
+++ b/media/libstagefright/include/MP3Decoder.h
@@ -42,6 +42,9 @@ protected:
 
 private:
     sp<MediaSource> mSource;
+    sp<MetaData> mMeta;
+    int32_t mNumChannels;
+
     bool mStarted;
 
     MediaBufferGroup *mBufferGroup;
@@ -49,10 +52,12 @@ private:
     tPVMP3DecoderExternal *mConfig;
     void *mDecoderBuf;
     int64_t mAnchorTimeUs;
-    int64_t mNumSamplesOutput;
+    int64_t mNumFramesOutput;
 
     MediaBuffer *mInputBuffer;
 
+    void init();
+
     MP3Decoder(const MP3Decoder &);
     MP3Decoder &operator=(const MP3Decoder &);
 };