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
91template <typename T>
92void SkipCutBuffer::submitInternal(const sp<T>& buffer) {
93    if (mCutBuffer == NULL) {
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
124void SkipCutBuffer::submit(const sp<ABuffer>& buffer) {
125    submitInternal(buffer);
126}
127
128void SkipCutBuffer::submit(const sp<MediaCodecBuffer>& buffer) {
129    submitInternal(buffer);
130}
131
132void SkipCutBuffer::clear() {
133    mWriteHead = mReadHead = 0;
134    mFrontPadding = mSkip;
135}
136
137void 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
171size_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
200size_t SkipCutBuffer::size() {
201    int32_t available = (mWriteHead - mReadHead);
202    if (available < 0) available += mCapacity;
203    return available;
204}
205
206}  // namespace android
207