1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 //#define LOG_NDEBUG 0
18 #define LOG_TAG "SkipCutBuffer"
19 #include <utils/Log.h>
20
21 #include <media/stagefright/foundation/ADebug.h>
22 #include <media/stagefright/MediaBuffer.h>
23 #include <media/stagefright/SkipCutBuffer.h>
24
25 namespace android {
26
SkipCutBuffer(size_t skip,size_t cut,size_t num16BitChannels)27 SkipCutBuffer::SkipCutBuffer(size_t skip, size_t cut, size_t num16BitChannels) {
28
29 mWriteHead = 0;
30 mReadHead = 0;
31 mCapacity = 0;
32 mCutBuffer = NULL;
33
34 if (num16BitChannels == 0 || num16BitChannels > INT32_MAX / 2) {
35 ALOGW("# channels out of range: %zu, using passthrough instead", num16BitChannels);
36 return;
37 }
38 size_t frameSize = num16BitChannels * 2;
39 if (skip > INT32_MAX / frameSize || cut > INT32_MAX / frameSize
40 || cut * frameSize > INT32_MAX - 4096) {
41 ALOGW("out of range skip/cut: %zu/%zu, using passthrough instead",
42 skip, cut);
43 return;
44 }
45 skip *= frameSize;
46 cut *= frameSize;
47
48 mFrontPadding = mSkip = skip;
49 mBackPadding = cut;
50 mCapacity = cut + 4096;
51 mCutBuffer = new (std::nothrow) char[mCapacity];
52 ALOGV("skipcutbuffer %zu %zu %d", skip, cut, mCapacity);
53 }
54
~SkipCutBuffer()55 SkipCutBuffer::~SkipCutBuffer() {
56 delete[] mCutBuffer;
57 }
58
submit(MediaBuffer * buffer)59 void SkipCutBuffer::submit(MediaBuffer *buffer) {
60 if (mCutBuffer == NULL) {
61 // passthrough mode
62 return;
63 }
64
65 int32_t offset = buffer->range_offset();
66 int32_t buflen = buffer->range_length();
67
68 // drop the initial data from the buffer if needed
69 if (mFrontPadding > 0) {
70 // still data left to drop
71 int32_t to_drop = (buflen < mFrontPadding) ? buflen : mFrontPadding;
72 offset += to_drop;
73 buflen -= to_drop;
74 buffer->set_range(offset, buflen);
75 mFrontPadding -= to_drop;
76 }
77
78
79 // append data to cutbuffer
80 char *src = ((char*) buffer->data()) + offset;
81 write(src, buflen);
82
83
84 // the mediabuffer is now empty. Fill it from cutbuffer, always leaving
85 // at least mBackPadding bytes in the cutbuffer
86 char *dst = (char*) buffer->data();
87 size_t copied = read(dst, buffer->size());
88 buffer->set_range(0, copied);
89 }
90
submit(const sp<ABuffer> & buffer)91 void SkipCutBuffer::submit(const sp<ABuffer>& buffer) {
92 if (mCutBuffer == NULL) {
93 // passthrough mode
94 return;
95 }
96
97 int32_t offset = buffer->offset();
98 int32_t buflen = buffer->size();
99
100 // drop the initial data from the buffer if needed
101 if (mFrontPadding > 0) {
102 // still data left to drop
103 int32_t to_drop = (buflen < mFrontPadding) ? buflen : mFrontPadding;
104 offset += to_drop;
105 buflen -= to_drop;
106 buffer->setRange(offset, buflen);
107 mFrontPadding -= to_drop;
108 }
109
110
111 // append data to cutbuffer
112 char *src = (char*) buffer->data();
113 write(src, buflen);
114
115
116 // the mediabuffer is now empty. Fill it from cutbuffer, always leaving
117 // at least mBackPadding bytes in the cutbuffer
118 char *dst = (char*) buffer->base();
119 size_t copied = read(dst, buffer->capacity());
120 buffer->setRange(0, copied);
121 }
122
clear()123 void SkipCutBuffer::clear() {
124 mWriteHead = mReadHead = 0;
125 mFrontPadding = mSkip;
126 }
127
write(const char * src,size_t num)128 void SkipCutBuffer::write(const char *src, size_t num) {
129 int32_t sizeused = (mWriteHead - mReadHead);
130 if (sizeused < 0) sizeused += mCapacity;
131
132 // Everything must fit. Make sure the buffer is a little larger than needed,
133 // so there is no ambiguity as to whether mWriteHead == mReadHead means buffer
134 // full or empty
135 size_t available = mCapacity - sizeused - 32;
136 if (available < num) {
137 int32_t newcapacity = mCapacity + (num - available);
138 char * newbuffer = new char[newcapacity];
139 memcpy(newbuffer, mCutBuffer, mCapacity);
140 delete [] mCutBuffer;
141 mCapacity = newcapacity;
142 mCutBuffer = newbuffer;
143 ALOGV("reallocated buffer at size %d", newcapacity);
144 }
145
146 size_t copyfirst = (mCapacity - mWriteHead);
147 if (copyfirst > num) copyfirst = num;
148 if (copyfirst) {
149 memcpy(mCutBuffer + mWriteHead, src, copyfirst);
150 num -= copyfirst;
151 src += copyfirst;
152 mWriteHead += copyfirst;
153 CHECK_LE(mWriteHead, mCapacity);
154 if (mWriteHead == mCapacity) mWriteHead = 0;
155 if (num) {
156 memcpy(mCutBuffer, src, num);
157 mWriteHead += num;
158 }
159 }
160 }
161
read(char * dst,size_t num)162 size_t SkipCutBuffer::read(char *dst, size_t num) {
163 int32_t available = (mWriteHead - mReadHead);
164 if (available < 0) available += mCapacity;
165
166 available -= mBackPadding;
167 if (available <=0) {
168 return 0;
169 }
170 if (available < int32_t(num)) {
171 num = available;
172 }
173
174 size_t copyfirst = (mCapacity - mReadHead);
175 if (copyfirst > num) copyfirst = num;
176 if (copyfirst) {
177 memcpy(dst, mCutBuffer + mReadHead, copyfirst);
178 num -= copyfirst;
179 dst += copyfirst;
180 mReadHead += copyfirst;
181 CHECK_LE(mReadHead, mCapacity);
182 if (mReadHead == mCapacity) mReadHead = 0;
183 if (num) {
184 memcpy(dst, mCutBuffer, num);
185 mReadHead += num;
186 }
187 }
188 return available;
189 }
190
size()191 size_t SkipCutBuffer::size() {
192 int32_t available = (mWriteHead - mReadHead);
193 if (available < 0) available += mCapacity;
194 return available;
195 }
196
197 } // namespace android
198