iphone sdk> 3.0。視頻縮略圖？

Question

從我已閱讀的蘋果不公開api允許開發人員使用當前sdk獲取電影的縮略圖。

任何人都可以共享一些代碼，以瞭解他們如何去做這件事嗎？ 我聽說您可以訪問相機選取器視圖，並在ui圖像選取器關閉之前找到圖像視圖。這看起來有點醜陋。

此外，我認爲使用ffmpeg抓取一個框架的電影，但不知道如何編譯它作爲一個庫的iphone線索。任何指針將不勝感激

Answer 1

在與縮略圖的電影相同的文件夾中有一個jpg。我只用手機錄製的視頻進行了測試，但效果很好。它的名稱與電影名稱不同，因此請獲取電影所在的目錄路徑並迭代爲.jpg，然後離開。

Answer 2

如果您使用UIImagePickerController獲取圖像，那麼JPG將不會存儲在tmp目錄中。我不確定這個問題的答案，但ffmpeg，更具體地說是它背後的庫，可能是您的選擇。

Answer 3

希望我的代碼可以幫助你們。它很醜。我認爲蘋果應該開放這種API。 當然，應該刪除所有NSLog（）。這只是爲了演示。

阿爾文

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{ 
// e.g. 
NSString *tempFilePath = [(NSURL *)[info valueForKey:UIImagePickerControllerMediaURL] absoluteString]; 
NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath); 
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture/capturedvideo.MOV 
tempFilePath = [[tempFilePath substringFromIndex:16] retain]; 
NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath); 
NSLog(@"===Try to save video to camera roll.==="); 
NSLog(@"UIVideoAtPathIsCompatibleWithSavedPhotosAlbum: %@",UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath)? @"YES":@"NO"); 
// Check if the video file can be saved to camera roll. 
    if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath)){ 
    // YES. Copy it to the camera roll. 
    UISaveVideoAtPathToSavedPhotosAlbum(tempFilePath, self, @selector(video:didFinishSavingWithError:contextInfo:), tempFilePath); 
} 

[self dismissModalViewControllerAnimated:YES]; 
} 

- (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(NSString *)contextInfo{ 
NSLog(@"didFinishSavingWithError--videoPath in camera roll:%@",videoPath); 
NSLog(@"didFinishSavingWithError--videoPath in temp directory:%@",contextInfo); 
// The thumbnail jpg should located in this directory. 
NSString *thumbnailDirectory = [[contextInfo stringByDeletingLastPathComponent] stringByDeletingLastPathComponent]; 

// Debug info. list all files in the directory of the video file. 
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture 
NSLog([contextInfo stringByDeletingLastPathComponent]); 
NSLog([[[NSFileManager defaultManager] contentsOfDirectoryAtPath:[contextInfo stringByDeletingLastPathComponent] error:nil] description]); 
// Debug info. list all files in the parent directory of the video file, i.e. the "~/tmp" directory. 
// e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp 
NSLog(thumbnailDirectory); 
NSLog([[[NSFileManager defaultManager] contentsOfDirectoryAtPath:thumbnailDirectory error:nil] description]); 
/////////////////// 

// Find the thumbnail for the video just recorded. 
NSString *file,*latestFile; 
NSDate *latestDate = [NSDate distantPast]; 
NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:[[contextInfo stringByDeletingLastPathComponent]stringByDeletingLastPathComponent]]; 
// Enumerate all files in the ~/tmp directory 
while (file = [dirEnum nextObject]) { 
    // Only check files with jpg extension. 
    if ([[file pathExtension] isEqualToString: @"jpg"]) { 
    NSLog(@"***latestDate:%@",latestDate); 
    NSLog(@"***file name:%@",file); 
    NSLog(@"***NSFileSize:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileSize"]); 
    NSLog(@"***NSFileModificationDate:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"]); 
    // Check if current jpg file is the latest one. 
    if ([(NSDate *)[[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"] compare:latestDate] == NSOrderedDescending){ 
    latestDate = [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"]; 
    latestFile = file; 
    NSLog(@"***latestFile changed:%@",latestFile); 
    } 
    } 
} 
// The thumbnail path. 
latestFile = [NSTemporaryDirectory() stringByAppendingPathComponent:latestFile]; 
NSLog(@"****** The thumbnail file should be this one:%@",latestFile); 

// Your code ... 
// Your code ... 
// Your code ... 
} 

Answer 4

只是想提供有關此更新。當你將你的選擇器設置爲UIImagePickerControllerSourceTypeCamera時，事情似乎在獲取縮略圖方面起作用。但是，當您嘗試從現有庫（即UIImagePickerControllerSourceTypePhotoLibrary） 中選擇縮略圖的.jpg時，將永遠不會創建。我甚至嘗試用UISaveVideoAtPathToSavedPhotosAlbum（...）重新保存，但仍然沒有骰子。看起來，縮略圖是在捕捉視頻時首先創建的。這是你「搶」它的唯一機會。之後它會移動到/ var/mobile/Media/DCIM /的子目錄中。雖然您可以真正列出縮略圖圖片並查看該圖片，但該文件不可讀且不可複製，因爲我相信該目錄受到保護。

如果任何人有解決這個問題，我將不勝感激，因爲在我的情況下，我需要從庫中選擇它後抓住現有視頻的縮略圖。

Answer 5

這裏有一個博客帖子有關使用ffmpeg的提取電影幀：

http://www.codza.com/extracting-frames-from-movies-on-iphone

在GitHub上相應的項目：iFrameExtractor

Answer 6

最好的方法，我發現...的MPMoviePlayerController thumbnailImageAtTime：timeOption

Answer 7

NSString *videoLink=[info objectForKey:@"UIImagePickerControllerMediaURL"]; 

MPMoviePlayerController *player = [[MPMoviePlayerController alloc] initWithContentURL:(NSURL*)videoLink]; 
UIImage *imageSel = [player thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame]; 
[player stop]; 
[player release];