The Tor Browser: content/media/omx/OMXCodecDescriptorUtil.cpp@97036ab72558 (annotated)

content/media/omx/OMXCodecDescriptorUtil.cpp@97036ab72558 (annotated)

content/media/omx/OMXCodecDescriptorUtil.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "OMXCodecDescriptorUtil.h"
 namespace android {
 // The utility functions in this file concatenate two AVC/H.264 parameter sets,
 // sequence parameter set(SPS) and picture parameter set(PPS), into byte stream
 // format or construct AVC decoder config descriptor blob from them.
 //
 // * NAL unit defined in ISO/IEC 14496-10 7.3.1
 // * SPS defined ISO/IEC 14496-10 7.3.2.1.1
 // * PPS defined in ISO/IEC 14496-10 7.3.2.2
 //
 // Byte stream format:
 // Start code <0x00 0x00 0x00 0x01>  (4 bytes)
 // --- (SPS) NAL unit ---
 //   ...                             (3 bits)
 //   NAL unit type <0x07>            (5 bits)
 //   SPS                             (3+ bytes)
 //     Profile                         (1 byte)
 //     Compatible profiles             (1 byte)
 //     Level                           (1 byte)
 //   ...
 // --- End ---
 // Start code <0x00 0x00 0x00 0x01>  (4 bytes)
 // --- (PPS) NAL unit ---
 //   ...                             (3 bits)
 //   NAL unit type <0x08>            (5 bits)
 //   PPS                             (1+ bytes)
 //   ...
 // --- End ---
 //
 // Descriptor format: (defined in ISO/IEC 14496-15 5.2.4.1.1)
 // --- Header (5 bytes) ---
 //   Version <0x01>       (1 byte)
 //   Profile              (1 byte)
 //   Compatible profiles  (1 byte)
 //   Level                (1 byte)
 //   Reserved <111111>    (6 bits)
 //   NAL length type      (2 bits)
 // --- Parameter sets ---
 //   Reserved <111>       (3 bits)
 //   Number of SPS        (5 bits)
 //   SPS                  (3+ bytes)
 //     Length               (2 bytes)
 //     SPS NAL unit         (1+ bytes)
 //   ...
 //   Number of PPS        (1 byte)
 //   PPS                  (3+ bytes)
 //     Length               (2 bytes)
 //     PPS NAL unit         (1+ bytes)
 //   ...
 // --- End ---
 // NAL unit start code.
 static const uint8_t kNALUnitStartCode[] = { 0x00, 0x00, 0x00, 0x01 };
 // NAL unit types.
 enum {
   kNALUnitTypeSPS = 0x07,   // Value for sequence parameter set.
   kNALUnitTypePPS = 0x08,   // Value for picture parameter set.
   kNALUnitTypeBad = -1,     // Malformed data.
 };
 // Sequence parameter set or picture parameter set.
 struct AVCParamSet {
   AVCParamSet(const uint8_t* aPtr, const size_t aSize)
     : mPtr(aPtr)
     , mSize(aSize)
   {
     MOZ_ASSERT(mPtr && mSize > 0);
   }
   size_t Size() {
     return mSize + 2; // 2 more bytes for length value.
   }
   // Append 2 bytes length value and NAL unit bitstream to aOutputBuf.
   void AppendTo(nsTArray<uint8_t>* aOutputBuf)
   {
     // 2 bytes length value.
     uint8_t size[] = {
       (mSize & 0xFF00) >> 8, // MSB.
       mSize & 0x00FF,        // LSB.
     };
     aOutputBuf->AppendElements(size, sizeof(size));
     aOutputBuf->AppendElements(mPtr, mSize);
   }
   const uint8_t* mPtr; // Pointer to NAL unit.
   const size_t mSize;  // NAL unit length in bytes.
 };
 // Convert SPS and PPS data into decoder config descriptor blob. The generated
 // blob will be appended to aOutputBuf.
 static status_t
 ConvertParamSetsToDescriptorBlob(sp<ABuffer>& aSPS, sp<ABuffer>& aPPS,
                                  nsTArray<uint8_t>* aOutputBuf)
 {
   // Strip start code in the input.
   AVCParamSet sps(aSPS->data() + sizeof(kNALUnitStartCode),
                   aSPS->size() - sizeof(kNALUnitStartCode));
   AVCParamSet pps(aPPS->data() + sizeof(kNALUnitStartCode),
                   aPPS->size() - sizeof(kNALUnitStartCode));
   size_t paramSetsSize = sps.Size() + pps.Size();
   // Profile/level info in SPS.
   uint8_t* info = aSPS->data() + 5;
   uint8_t header[] = {
 x01,     // Version.
     info[0],  // Profile.
     info[1],  // Compatible profiles.
     info[2],  // Level.
 xFF,     // 6 bits reserved value <111111> + 2 bits NAL length type <11>
   };
   // Reserve 1 byte for number of SPS & another 1 for number of PPS.
   aOutputBuf->SetCapacity(sizeof(header) + paramSetsSize + 2);
   // Build the blob.
   aOutputBuf->AppendElements(header, sizeof(header)); // 5 bytes Header.
   aOutputBuf->AppendElement(0xE0 | 1); // 3 bits <111> + 5 bits number of SPS.
   sps.AppendTo(aOutputBuf); // SPS NALU data.
   aOutputBuf->AppendElement(1); // 1 byte number of PPS.
   pps.AppendTo(aOutputBuf); // PPS NALU data.
   return OK;
 }
 static int
 NALType(sp<ABuffer>& aBuffer)
 {
   if (aBuffer == nullptr) {
     return kNALUnitTypeBad;
   }
   // Start code?
   uint8_t* data = aBuffer->data();
   if (aBuffer->size() <= 4 ||
       memcmp(data, kNALUnitStartCode, sizeof(kNALUnitStartCode))) {
     return kNALUnitTypeBad;
   }
   return data[4] & 0x1F;
 }
 // Generate AVC/H.264 decoder config blob.
 // See MPEG4Writer::Track::makeAVCCodecSpecificData() and
 // MPEG4Writer::Track::writeAvccBox() implementation in libstagefright.
 status_t
 GenerateAVCDescriptorBlob(sp<AMessage>& aConfigData,
                           nsTArray<uint8_t>* aOutputBuf,
                           OMXVideoEncoder::BlobFormat aFormat)
 {
   // Search for parameter sets using key "csd-0" and "csd-1".
   char key[6] = "csd-";
   sp<ABuffer> sps;
   sp<ABuffer> pps;
   for (int i = 0; i < 2; i++) {
     snprintf(key + 4, 2, "%d", i);
     sp<ABuffer> paramSet;
     bool found = aConfigData->findBuffer(key, &paramSet);
     int type = NALType(paramSet);
     bool valid = ((type == kNALUnitTypeSPS) || (type == kNALUnitTypePPS));
     MOZ_ASSERT(found && valid);
     if (!found || !valid) {
       return ERROR_MALFORMED;
     }
     switch (type) {
       case kNALUnitTypeSPS:
         sps = paramSet;
         break;
       case kNALUnitTypePPS:
         pps = paramSet;
         break;
       default:
         NS_NOTREACHED("Should not get here!");
     }
   }
   MOZ_ASSERT(sps != nullptr && pps != nullptr);
   if (sps == nullptr || pps == nullptr) {
     return ERROR_MALFORMED;
   }
   status_t result = OK;
   if (aFormat == OMXVideoEncoder::BlobFormat::AVC_NAL) {
     // SPS + PPS.
     aOutputBuf->AppendElements(sps->data(), sps->size());
     aOutputBuf->AppendElements(pps->data(), pps->size());
     return OK;
   } else {
     status_t result = ConvertParamSetsToDescriptorBlob(sps, pps, aOutputBuf);
     MOZ_ASSERT(result == OK);
     return result;
   }
 }
 } // namespace android

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content/media/omx/OMXCodecDescriptorUtil.cpp@97036ab72558 (annotated)

content/media/omx/OMXCodecDescriptorUtil.cpp