贴点我的转换代码
(void)videoWithUrl:(NSURL *)url withFilePath:(NSString *)filePath
{
[[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];
static const NSUInteger BufferSize = 1024*1024;
ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
if (url) {
[assetLibrary assetForURL:url resultBlock:^(ALAsset *asset) {
ALAssetRepresentation *rep=[asset defaultRepresentation];
uint8_t *buffer = calloc(BufferSize, sizeof(*buffer));
NSUInteger offset = 0, bytesRead = 0;
do {
bytesRead = [rep getBytes:buffer fromOffset:offset length:BufferSize error:nil];
[handle writeData:[NSData dataWithBytesNoCopy:buffer length:bytesRead freeWhenDone:NO]];
offset += bytesRead;
} while (bytesRead > 0);
free(buffer);