android录制更大视频文件的修改

android录像的视频文件最大只有2GB，录制更大视频文件的修改

1. 首先Application需要Set 64bit Offset的属性给Writer.

frameworks/base/media/java/android/media/MediaRecorder.java
public void setVideoEncodingBitRate(int bitRate)
{
...
setParameter("video-param-encoding-bitrate=" + bitRate);
// To revise the 2GB file size limit. 添加下面这一行
setParameter("param-use-64bit-offset=1");
}

2. MPEG4Writer中的file cache需要修改为64bit.
frameworks/av/include/media/stagefright/MPEG4Writer.h
这个Class MPEG4FileCacheWriter中的Define.
int seek(off_t offset, int refpos);
修改为：
int seek(off64_t offset, int refpos);
frameworks/av/media/libstagefright/MPEG4Writer.cpp
int MPEG4FileCacheWriter::seek(off_t offset,int refpos)
修改为：
int MPEG4FileCacheWriter::seek(off64_t offset,int refpos)

3. 如果想把录像文件的大小限制在4GB以内的话，还需要进行下面的修改：
frameworks/av/media/libstagefright/MPEG4Writer.cpp
static const int64_t kMax32BitFileSize = 0x007fffffffLL;
=>
static const int64_t kMax32BitFileSize = 0x00ffffffffLL;
把下面这个if (mUse32BitOffset) 条件注释掉就OK了。
status_t MPEG4Writer::start(MetaData *param){
... ...
//if (mUse32BitOffset) {
// Implicit 32 bit file size limit
if (mMaxFileSizeLimitBytes == 0) {
mMaxFileSizeLimitBytes = kMax32BitFileSize;
}
// If file size is set to be larger than the 32 bit file
// size limit, treat it as an error.
if (mMaxFileSizeLimitBytes > kMax32BitFileSize) {
ALOGW("32-bit file size limit (%lld bytes) too big. "
"It is changed to %lld bytes",
mMaxFileSizeLimitBytes, kMax32BitFileSize);
mMaxFileSizeLimitBytes = kMax32BitFileSize;
}
//}

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