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comparison: content/media/omx/OMXCodecDescriptorUtil.cpp

content/media/omx/OMXCodecDescriptorUtil.cpp

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1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
4 * You can obtain one at http://mozilla.org/MPL/2.0/. */
5
6 #include "OMXCodecDescriptorUtil.h"
7
8 namespace android {
9
10 // The utility functions in this file concatenate two AVC/H.264 parameter sets,
11 // sequence parameter set(SPS) and picture parameter set(PPS), into byte stream
12 // format or construct AVC decoder config descriptor blob from them.
13 //
14 // * NAL unit defined in ISO/IEC 14496-10 7.3.1
15 // * SPS defined ISO/IEC 14496-10 7.3.2.1.1
16 // * PPS defined in ISO/IEC 14496-10 7.3.2.2
17 //
18 // Byte stream format:
19 // Start code <0x00 0x00 0x00 0x01> (4 bytes)
20 // --- (SPS) NAL unit ---
21 // ... (3 bits)
22 // NAL unit type <0x07> (5 bits)
23 // SPS (3+ bytes)
24 // Profile (1 byte)
25 // Compatible profiles (1 byte)
26 // Level (1 byte)
27 // ...
28 // --- End ---
29 // Start code <0x00 0x00 0x00 0x01> (4 bytes)
30 // --- (PPS) NAL unit ---
31 // ... (3 bits)
32 // NAL unit type <0x08> (5 bits)
33 // PPS (1+ bytes)
34 // ...
35 // --- End ---
36 //
37 // Descriptor format: (defined in ISO/IEC 14496-15 5.2.4.1.1)
38 // --- Header (5 bytes) ---
39 // Version <0x01> (1 byte)
40 // Profile (1 byte)
41 // Compatible profiles (1 byte)
42 // Level (1 byte)
43 // Reserved <111111> (6 bits)
44 // NAL length type (2 bits)
45 // --- Parameter sets ---
46 // Reserved <111> (3 bits)
47 // Number of SPS (5 bits)
48 // SPS (3+ bytes)
49 // Length (2 bytes)
50 // SPS NAL unit (1+ bytes)
51 // ...
52 // Number of PPS (1 byte)
53 // PPS (3+ bytes)
54 // Length (2 bytes)
55 // PPS NAL unit (1+ bytes)
56 // ...
57 // --- End ---
58
59 // NAL unit start code.
60 static const uint8_t kNALUnitStartCode[] = { 0x00, 0x00, 0x00, 0x01 };
61
62 // NAL unit types.
63 enum {
64 kNALUnitTypeSPS = 0x07, // Value for sequence parameter set.
65 kNALUnitTypePPS = 0x08, // Value for picture parameter set.
66 kNALUnitTypeBad = -1, // Malformed data.
67 };
68
69 // Sequence parameter set or picture parameter set.
70 struct AVCParamSet {
71 AVCParamSet(const uint8_t* aPtr, const size_t aSize)
72 : mPtr(aPtr)
73 , mSize(aSize)
74 {
75 MOZ_ASSERT(mPtr && mSize > 0);
76 }
77
78 size_t Size() {
79 return mSize + 2; // 2 more bytes for length value.
80 }
81
82 // Append 2 bytes length value and NAL unit bitstream to aOutputBuf.
83 void AppendTo(nsTArray<uint8_t>* aOutputBuf)
84 {
85 // 2 bytes length value.
86 uint8_t size[] = {
87 (mSize & 0xFF00) >> 8, // MSB.
88 mSize & 0x00FF, // LSB.
89 };
90 aOutputBuf->AppendElements(size, sizeof(size));
91
92 aOutputBuf->AppendElements(mPtr, mSize);
93 }
94
95 const uint8_t* mPtr; // Pointer to NAL unit.
96 const size_t mSize; // NAL unit length in bytes.
97 };
98
99 // Convert SPS and PPS data into decoder config descriptor blob. The generated
100 // blob will be appended to aOutputBuf.
101 static status_t
102 ConvertParamSetsToDescriptorBlob(sp<ABuffer>& aSPS, sp<ABuffer>& aPPS,
103 nsTArray<uint8_t>* aOutputBuf)
104 {
105 // Strip start code in the input.
106 AVCParamSet sps(aSPS->data() + sizeof(kNALUnitStartCode),
107 aSPS->size() - sizeof(kNALUnitStartCode));
108 AVCParamSet pps(aPPS->data() + sizeof(kNALUnitStartCode),
109 aPPS->size() - sizeof(kNALUnitStartCode));
110 size_t paramSetsSize = sps.Size() + pps.Size();
111
112 // Profile/level info in SPS.
113 uint8_t* info = aSPS->data() + 5;
114
115 uint8_t header[] = {
116 0x01, // Version.
117 info[0], // Profile.
118 info[1], // Compatible profiles.
119 info[2], // Level.
120 0xFF, // 6 bits reserved value <111111> + 2 bits NAL length type <11>
121 };
122
123 // Reserve 1 byte for number of SPS & another 1 for number of PPS.
124 aOutputBuf->SetCapacity(sizeof(header) + paramSetsSize + 2);
125 // Build the blob.
126 aOutputBuf->AppendElements(header, sizeof(header)); // 5 bytes Header.
127 aOutputBuf->AppendElement(0xE0 | 1); // 3 bits <111> + 5 bits number of SPS.
128 sps.AppendTo(aOutputBuf); // SPS NALU data.
129 aOutputBuf->AppendElement(1); // 1 byte number of PPS.
130 pps.AppendTo(aOutputBuf); // PPS NALU data.
131
132 return OK;
133 }
134
135 static int
136 NALType(sp<ABuffer>& aBuffer)
137 {
138 if (aBuffer == nullptr) {
139 return kNALUnitTypeBad;
140 }
141 // Start code?
142 uint8_t* data = aBuffer->data();
143 if (aBuffer->size() <= 4 ||
144 memcmp(data, kNALUnitStartCode, sizeof(kNALUnitStartCode))) {
145 return kNALUnitTypeBad;
146 }
147
148 return data[4] & 0x1F;
149 }
150
151 // Generate AVC/H.264 decoder config blob.
152 // See MPEG4Writer::Track::makeAVCCodecSpecificData() and
153 // MPEG4Writer::Track::writeAvccBox() implementation in libstagefright.
154 status_t
155 GenerateAVCDescriptorBlob(sp<AMessage>& aConfigData,
156 nsTArray<uint8_t>* aOutputBuf,
157 OMXVideoEncoder::BlobFormat aFormat)
158 {
159 // Search for parameter sets using key "csd-0" and "csd-1".
160 char key[6] = "csd-";
161 sp<ABuffer> sps;
162 sp<ABuffer> pps;
163 for (int i = 0; i < 2; i++) {
164 snprintf(key + 4, 2, "%d", i);
165 sp<ABuffer> paramSet;
166 bool found = aConfigData->findBuffer(key, &paramSet);
167 int type = NALType(paramSet);
168 bool valid = ((type == kNALUnitTypeSPS) || (type == kNALUnitTypePPS));
169
170 MOZ_ASSERT(found && valid);
171 if (!found || !valid) {
172 return ERROR_MALFORMED;
173 }
174
175 switch (type) {
176 case kNALUnitTypeSPS:
177 sps = paramSet;
178 break;
179 case kNALUnitTypePPS:
180 pps = paramSet;
181 break;
182 default:
183 NS_NOTREACHED("Should not get here!");
184 }
185 }
186
187 MOZ_ASSERT(sps != nullptr && pps != nullptr);
188 if (sps == nullptr || pps == nullptr) {
189 return ERROR_MALFORMED;
190 }
191
192 status_t result = OK;
193 if (aFormat == OMXVideoEncoder::BlobFormat::AVC_NAL) {
194 // SPS + PPS.
195 aOutputBuf->AppendElements(sps->data(), sps->size());
196 aOutputBuf->AppendElements(pps->data(), pps->size());
197 return OK;
198 } else {
199 status_t result = ConvertParamSetsToDescriptorBlob(sps, pps, aOutputBuf);
200 MOZ_ASSERT(result == OK);
201 return result;
202 }
203 }
204
205 } // namespace android

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