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
25namespace android {
26
27SkipCutBuffer::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
55SkipCutBuffer::~SkipCutBuffer() {
56    delete[] mCutBuffer;
57}
58
59void 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
91void 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
123void SkipCutBuffer::clear() {
124    mWriteHead = mReadHead = 0;
125    mFrontPadding = mSkip;
126}
127
128void 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
162size_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
191size_t SkipCutBuffer::size() {
192    int32_t available = (mWriteHead - mReadHead);
193    if (available < 0) available += mCapacity;
194    return available;
195}
196
197}  // namespace android
198