Some refactoring and added support for another form of vbr headers.

related-to-bug: 3172324

Change-Id: Ic364da09eac7f0a815f9ceb719b6baa8a76e3730

1 files changed, 223 insertions, 0 deletions

diff --git a/media/libstagefright/XINGSeeker.cpp b/media/libstagefright/XINGSeeker.cpp
new file mode 100644
index 0000000..72f260e
--- /dev/null
+++ b/media/libstagefright/XINGSeeker.cpp
@@ -0,0 +1,223 @@
+/*
+ * 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.
+ */
+
+#include "include/XINGSeeker.h"
+
+#include <media/stagefright/DataSource.h>
+#include <media/stagefright/Utils.h>
+
+namespace android {
+
+static bool parse_xing_header(
+        const sp<DataSource> &source, off_t first_frame_pos,
+        int32_t *frame_number = NULL, int32_t *byte_number = NULL,
+        char *table_of_contents = NULL, int32_t *quality_indicator = NULL,
+        int64_t *duration = NULL);
+
+// static
+sp<XINGSeeker> XINGSeeker::CreateFromSource(
+        const sp<DataSource> &source, off_t first_frame_pos) {
+    sp<XINGSeeker> seeker = new XINGSeeker;
+
+    seeker->mFirstFramePos = first_frame_pos;
+
+    if (!parse_xing_header(
+                source, first_frame_pos,
+                NULL, &seeker->mSizeBytes, seeker->mTableOfContents,
+                NULL, &seeker->mDurationUs)) {
+        return NULL;
+    }
+
+    LOGI("Found XING header.");
+
+    return seeker;
+}
+
+XINGSeeker::XINGSeeker()
+    : mDurationUs(-1),
+      mSizeBytes(0) {
+}
+
+bool XINGSeeker::getDuration(int64_t *durationUs) {
+    if (mDurationUs < 0) {
+        return false;
+    }
+
+    *durationUs = mDurationUs;
+
+    return true;
+}
+
+bool XINGSeeker::getOffsetForTime(int64_t *timeUs, off_t *pos) {
+    if (mSizeBytes == 0 || mTableOfContents[0] <= 0 || mDurationUs < 0) {
+        return false;
+    }
+
+    float percent = (float)(*timeUs) * 100 / mDurationUs;
+    float fx;
+    if( percent <= 0.0f ) {
+        fx = 0.0f;
+    } else if( percent >= 100.0f ) {
+        fx = 256.0f;
+    } else {
+        int a = (int)percent;
+        float fa, fb;
+        if ( a == 0 ) {
+            fa = 0.0f;
+        } else {
+            fa = (float)mTableOfContents[a-1];
+        }
+        if ( a < 99 ) {
+            fb = (float)mTableOfContents[a];
+        } else {
+            fb = 256.0f;
+        }
+        fx = fa + (fb-fa)*(percent-a);
+    }
+
+    *pos = (int)((1.0f/256.0f)*fx*mSizeBytes) + mFirstFramePos;
+
+    return true;
+}
+
+static bool parse_xing_header(
+        const sp<DataSource> &source, off_t first_frame_pos,
+        int32_t *frame_number, int32_t *byte_number,
+        char *table_of_contents, int32_t *quality_indicator,
+        int64_t *duration) {
+    if (frame_number) {
+        *frame_number = 0;
+    }
+    if (byte_number) {
+        *byte_number = 0;
+    }
+    if (table_of_contents) {
+        table_of_contents[0] = 0;
+    }
+    if (quality_indicator) {
+        *quality_indicator = 0;
+    }
+    if (duration) {
+        *duration = 0;
+    }
+
+    uint8_t buffer[4];
+    int offset = first_frame_pos;
+    if (source->readAt(offset, &buffer, 4) < 4) { // get header
+        return false;
+    }
+    offset += 4;
+
+    uint8_t id, layer, sr_index, mode;
+    layer = (buffer[1] >> 1) & 3;
+    id = (buffer[1] >> 3) & 3;
+    sr_index = (buffer[2] >> 2) & 3;
+    mode = (buffer[3] >> 6) & 3;
+    if (layer == 0) {
+        return false;
+    }
+    if (id == 1) {
+        return false;
+    }
+    if (sr_index == 3) {
+        return false;
+    }
+    // determine offset of XING header
+    if(id&1) { // mpeg1
+        if (mode != 3) offset += 32;
+        else offset += 17;
+    } else { // mpeg2
+        if (mode != 3) offset += 17;
+        else offset += 9;
+    }
+
+    if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID
+        return false;
+    }
+    offset += 4;
+    // Check XING ID
+    if ((buffer[0] != 'X') || (buffer[1] != 'i')
+                || (buffer[2] != 'n') || (buffer[3] != 'g')) {
+        if ((buffer[0] != 'I') || (buffer[1] != 'n')
+                    || (buffer[2] != 'f') || (buffer[3] != 'o')) {
+            return false;
+        }
+    }
+
+    if (source->readAt(offset, &buffer, 4) < 4) { // flags
+        return false;
+    }
+    offset += 4;
+    uint32_t flags = U32_AT(buffer);
+
+    if (flags & 0x0001) {  // Frames field is present
+        if (source->readAt(offset, buffer, 4) < 4) {
+             return false;
+        }
+        if (frame_number) {
+           *frame_number = U32_AT(buffer);
+        }
+        int32_t frame = U32_AT(buffer);
+        // Samples per Frame: 1. index = MPEG Version ID, 2. index = Layer
+        const int samplesPerFrames[2][3] =
+        {
+            { 384, 1152, 576  }, // MPEG 2, 2.5: layer1, layer2, layer3
+            { 384, 1152, 1152 }, // MPEG 1: layer1, layer2, layer3
+        };
+        // sampling rates in hertz: 1. index = MPEG Version ID, 2. index = sampling rate index
+        const int samplingRates[4][3] =
+        {
+            { 11025, 12000, 8000,  },    // MPEG 2.5
+            { 0,     0,     0,     },    // reserved
+            { 22050, 24000, 16000, },    // MPEG 2
+            { 44100, 48000, 32000, }     // MPEG 1
+        };
+        if (duration) {
+            *duration = (int64_t)frame * samplesPerFrames[id&1][3-layer] * 1000000LL
+                / samplingRates[id][sr_index];
+        }
+        offset += 4;
+    }
+    if (flags & 0x0002) {  // Bytes field is present
+        if (byte_number) {
+            if (source->readAt(offset, buffer, 4) < 4) {
+                return false;
+            }
+            *byte_number = U32_AT(buffer);
+        }
+        offset += 4;
+    }
+    if (flags & 0x0004) {  // TOC field is present
+       if (table_of_contents) {
+            if (source->readAt(offset + 1, table_of_contents, 99) < 99) {
+                return false;
+            }
+        }
+        offset += 100;
+    }
+    if (flags & 0x0008) {  // Quality indicator field is present
+        if (quality_indicator) {
+            if (source->readAt(offset, buffer, 4) < 4) {
+                return false;
+            }
+            *quality_indicator = U32_AT(buffer);
+        }
+    }
+    return true;
+}
+
+}  // namespace android
+