1 files changed, 165 insertions, 0 deletions
diff --git a/media/libstagefright/VBRISeeker.cpp b/media/libstagefright/VBRISeeker.cpp
new file mode 100644
index 0000000..bcba874
--- /dev/null
+++ b/media/libstagefright/VBRISeeker.cpp
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "VBRISeeker"
+#include <utils/Log.h>
+
+#include "include/VBRISeeker.h"
+
+#include "include/avc_utils.h"
+#include "include/MP3Extractor.h"
+
+#include <media/stagefright/foundation/ADebug.h>
+#include <media/stagefright/DataSource.h>
+#include <media/stagefright/Utils.h>
+
+namespace android {
+
+static uint32_t U24_AT(const uint8_t *ptr) {
+    return ptr[0] << 16 | ptr[1] << 8 | ptr[2];
+}
+
+// static
+sp<VBRISeeker> VBRISeeker::CreateFromSource(
+        const sp<DataSource> &source, off64_t post_id3_pos) {
+    off64_t pos = post_id3_pos;
+
+    uint8_t header[4];
+    ssize_t n = source->readAt(pos, header, sizeof(header));
+    if (n < (ssize_t)sizeof(header)) {
+        return NULL;
+    }
+
+    uint32_t tmp = U32_AT(&header[0]);
+    size_t frameSize;
+    int sampleRate;
+    if (!GetMPEGAudioFrameSize(tmp, &frameSize, &sampleRate)) {
+        return NULL;
+    }
+
+    // VBRI header follows 32 bytes after the header _ends_.
+    pos += sizeof(header) + 32;
+
+    uint8_t vbriHeader[26];
+    n = source->readAt(pos, vbriHeader, sizeof(vbriHeader));
+    if (n < (ssize_t)sizeof(vbriHeader)) {
+        return NULL;
+    }
+
+    if (memcmp(vbriHeader, "VBRI", 4)) {
+        return NULL;
+    }
+
+    size_t numFrames = U32_AT(&vbriHeader[14]);
+
+    int64_t durationUs =
+        numFrames * 1000000ll * (sampleRate >= 32000 ? 1152 : 576) / sampleRate;
+
+    ALOGV("duration = %.2f secs", durationUs / 1E6);
+
+    size_t numEntries = U16_AT(&vbriHeader[18]);
+    size_t entrySize = U16_AT(&vbriHeader[22]);
+    size_t scale = U16_AT(&vbriHeader[20]);
+
+    ALOGV("%d entries, scale=%d, size_per_entry=%d",
+         numEntries,
+         scale,
+         entrySize);
+
+    size_t totalEntrySize = numEntries * entrySize;
+    uint8_t *buffer = new uint8_t[totalEntrySize];
+
+    n = source->readAt(pos + sizeof(vbriHeader), buffer, totalEntrySize);
+    if (n < (ssize_t)totalEntrySize) {
+        delete[] buffer;
+        buffer = NULL;
+
+        return NULL;
+    }
+
+    sp<VBRISeeker> seeker = new VBRISeeker;
+    seeker->mBasePos = post_id3_pos + frameSize;
+    seeker->mDurationUs = durationUs;
+
+    off64_t offset = post_id3_pos;
+    for (size_t i = 0; i < numEntries; ++i) {
+        uint32_t numBytes;
+        switch (entrySize) {
+            case 1: numBytes = buffer[i]; break;
+            case 2: numBytes = U16_AT(buffer + 2 * i); break;
+            case 3: numBytes = U24_AT(buffer + 3 * i); break;
+            default:
+            {
+                CHECK_EQ(entrySize, 4u);
+                numBytes = U32_AT(buffer + 4 * i); break;
+            }
+        }
+
+        numBytes *= scale;
+
+        seeker->mSegments.push(numBytes);
+
+        ALOGV("entry #%d: %d offset 0x%08lx", i, numBytes, offset);
+        offset += numBytes;
+    }
+
+    delete[] buffer;
+    buffer = NULL;
+
+    ALOGI("Found VBRI header.");
+
+    return seeker;
+}
+
+VBRISeeker::VBRISeeker()
+    : mDurationUs(-1) {
+}
+
+bool VBRISeeker::getDuration(int64_t *durationUs) {
+    if (mDurationUs < 0) {
+        return false;
+    }
+
+    *durationUs = mDurationUs;
+
+    return true;
+}
+
+bool VBRISeeker::getOffsetForTime(int64_t *timeUs, off64_t *pos) {
+    if (mDurationUs < 0) {
+        return false;
+    }
+
+    int64_t segmentDurationUs = mDurationUs / mSegments.size();
+
+    int64_t nowUs = 0;
+    *pos = mBasePos;
+    size_t segmentIndex = 0;
+    while (segmentIndex < mSegments.size() && nowUs < *timeUs) {
+        nowUs += segmentDurationUs;
+        *pos += mSegments.itemAt(segmentIndex++);
+    }
+
+    ALOGV("getOffsetForTime %lld us => 0x%08lx", *timeUs, *pos);
+
+    *timeUs = nowUs;
+
+    return true;
+}
+
+}  // namespace android
+