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 = nullptr;
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 == nullptr) {
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
91 template <typename T>
submitInternal(const sp<T> & buffer)92 void SkipCutBuffer::submitInternal(const sp<T>& buffer) {
93 if (mCutBuffer == nullptr) {
94 // passthrough mode
95 return;
96 }
97
98 int32_t offset = buffer->offset();
99 int32_t buflen = buffer->size();
100
101 // drop the initial data from the buffer if needed
102 if (mFrontPadding > 0) {
103 // still data left to drop
104 int32_t to_drop = (buflen < mFrontPadding) ? buflen : mFrontPadding;
105 offset += to_drop;
106 buflen -= to_drop;
107 buffer->setRange(offset, buflen);
108 mFrontPadding -= to_drop;
109 }
110
111
112 // append data to cutbuffer
113 char *src = (char*) buffer->data();
114 write(src, buflen);
115
116
117 // the mediabuffer is now empty. Fill it from cutbuffer, always leaving
118 // at least mBackPadding bytes in the cutbuffer
119 char *dst = (char*) buffer->base();
120 size_t copied = read(dst, buffer->capacity());
121 buffer->setRange(0, copied);
122 }
123
submit(const sp<ABuffer> & buffer)124 void SkipCutBuffer::submit(const sp<ABuffer>& buffer) {
125 submitInternal(buffer);
126 }
127
submit(const sp<MediaCodecBuffer> & buffer)128 void SkipCutBuffer::submit(const sp<MediaCodecBuffer>& buffer) {
129 submitInternal(buffer);
130 }
131
clear()132 void SkipCutBuffer::clear() {
133 mWriteHead = mReadHead = 0;
134 mFrontPadding = mSkip;
135 }
136
write(const char * src,size_t num)137 void SkipCutBuffer::write(const char *src, size_t num) {
138 int32_t sizeused = (mWriteHead - mReadHead);
139 if (sizeused < 0) sizeused += mCapacity;
140
141 // Everything must fit. Make sure the buffer is a little larger than needed,
142 // so there is no ambiguity as to whether mWriteHead == mReadHead means buffer
143 // full or empty
144 size_t available = mCapacity - sizeused - 32;
145 if (available < num) {
146 int32_t newcapacity = mCapacity + (num - available);
147 char * newbuffer = new char[newcapacity];
148 memcpy(newbuffer, mCutBuffer, mCapacity);
149 delete [] mCutBuffer;
150 mCapacity = newcapacity;
151 mCutBuffer = newbuffer;
152 ALOGV("reallocated buffer at size %d", newcapacity);
153 }
154
155 size_t copyfirst = (mCapacity - mWriteHead);
156 if (copyfirst > num) copyfirst = num;
157 if (copyfirst) {
158 memcpy(mCutBuffer + mWriteHead, src, copyfirst);
159 num -= copyfirst;
160 src += copyfirst;
161 mWriteHead += copyfirst;
162 CHECK_LE(mWriteHead, mCapacity);
163 if (mWriteHead == mCapacity) mWriteHead = 0;
164 if (num) {
165 memcpy(mCutBuffer, src, num);
166 mWriteHead += num;
167 }
168 }
169 }
170
read(char * dst,size_t num)171 size_t SkipCutBuffer::read(char *dst, size_t num) {
172 int32_t available = (mWriteHead - mReadHead);
173 if (available < 0) available += mCapacity;
174
175 available -= mBackPadding;
176 if (available <=0) {
177 return 0;
178 }
179 if (available < int32_t(num)) {
180 num = available;
181 }
182
183 size_t copyfirst = (mCapacity - mReadHead);
184 if (copyfirst > num) copyfirst = num;
185 if (copyfirst) {
186 memcpy(dst, mCutBuffer + mReadHead, copyfirst);
187 num -= copyfirst;
188 dst += copyfirst;
189 mReadHead += copyfirst;
190 CHECK_LE(mReadHead, mCapacity);
191 if (mReadHead == mCapacity) mReadHead = 0;
192 if (num) {
193 memcpy(dst, mCutBuffer, num);
194 mReadHead += num;
195 }
196 }
197 return available;
198 }
199
size()200 size_t SkipCutBuffer::size() {
201 int32_t available = (mWriteHead - mReadHead);
202 if (available < 0) available += mCapacity;
203 return available;
204 }
205
206 } // namespace android
207