使用 OpenGL-ES 在 iOS 上播放视频

发布于 2024-12-07 20:01:27 字数 1789 浏览 0 评论 0原文

我正在尝试在 iOS 上播放视频 (MP4/H.263)，但得到的结果非常模糊。以下是初始化资产读取的代码：

mTextureHandle = [self createTexture:CGSizeMake(400,400)];

NSURL * url = [NSURL fileURLWithPath:file];    
mAsset = [[AVURLAsset alloc] initWithURL:url options:NULL];

NSArray * tracks = [mAsset tracksWithMediaType:AVMediaTypeVideo];

mTrack = [tracks objectAtIndex:0];

NSLog(@"Tracks: %i", [tracks count]);

NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary * settings = [[NSDictionary alloc] initWithObjectsAndKeys:value, key, nil];

mOutput = [[AVAssetReaderTrackOutput alloc] 
            initWithTrack:mTrack outputSettings:settings];


mReader = [[AVAssetReader alloc] initWithAsset:mAsset error:nil];
[mReader addOutput:mOutput];

对于读者初始化来说就这么多，现在是实际的纹理：

CMSampleBufferRef sampleBuffer = [mOutput copyNextSampleBuffer];    
CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress( pixelBuffer, 0 );

glBindTexture(GL_TEXTURE_2D, mTextureHandle);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 600, 400, 0, GL_BGRA_EXT, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddress( pixelBuffer ));    
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );    
CFRelease(sampleBuffer);

一切正常......除了渲染的图像看起来像这样；切片和倾斜？

在此处输入图像描述

我什至尝试研究 AVAssetTrack 的首选转换矩阵，以无济于事，因为它总是返回CGAffineTransformIdentity。

旁注：如果我将源切换到相机，图像就会渲染得很好。我错过了一些减压步骤吗？这不应该由资产读取器处理吗？

谢谢！

代码： https://github.com/shaded-enmity/objcpp-opengl-video< /a>

原文

I'm trying to play a video (MP4/H.263) on iOS, but getting really fuzzy results.
Here's the code to initialize the asset reading:

mTextureHandle = [self createTexture:CGSizeMake(400,400)];

NSURL * url = [NSURL fileURLWithPath:file];    
mAsset = [[AVURLAsset alloc] initWithURL:url options:NULL];

NSArray * tracks = [mAsset tracksWithMediaType:AVMediaTypeVideo];

mTrack = [tracks objectAtIndex:0];

NSLog(@"Tracks: %i", [tracks count]);

NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary * settings = [[NSDictionary alloc] initWithObjectsAndKeys:value, key, nil];

mOutput = [[AVAssetReaderTrackOutput alloc] 
            initWithTrack:mTrack outputSettings:settings];


mReader = [[AVAssetReader alloc] initWithAsset:mAsset error:nil];
[mReader addOutput:mOutput];

So much for the reader init, now the actual texturing:

CMSampleBufferRef sampleBuffer = [mOutput copyNextSampleBuffer];    
CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress( pixelBuffer, 0 );

glBindTexture(GL_TEXTURE_2D, mTextureHandle);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 600, 400, 0, GL_BGRA_EXT, GL_UNSIGNED_BYTE, CVPixelBufferGetBaseAddress( pixelBuffer ));    
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );    
CFRelease(sampleBuffer);

Everything works well ... except the rendered image looks like this; sliced and skewed?

enter image description here

I've even tried looking into AVAssetTrack's preferred transformation matrix, to no avail, since it always returns CGAffineTransformIdentity.

Side-note: If I switch the source to camera, the image gets rendered fine. Am I missing some decompression step? Shouldn't that be handled by the asset reader?

Thanks!

Code: https://github.com/shaded-enmity/objcpp-opengl-video

分享到QQ

分享到微博