Question

我正在尝试使用iVidCap插件制作视频并为其添加音频。基本上与这个问题完全相同：Writing video + generated audio to AVAssetWriterInput, audio stuttering。我已经使用这篇文章中的代码作为自己尝试修改iVidCap.mm文件的基础，但应用程序总是在endRecordingSession中崩溃。

我不确定如何修改endRecordingSession来容纳音频（原始插件只是创建一个视频文件）。这是功能：

- (int) endRecordingSession: (VideoDisposition) action {

NSLog(@"Start endRecordingSession");
NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

NSLog(@"Auto released pool");

NSString *filePath;
BOOL success = false;

[videoWriterInput markAsFinished];
NSLog(@"Mark video writer input as finished");
//[audioWriterInput markAsFinished];

// Wait for the video status to become known.
// Is this really doing anything?
int status = videoWriter.status;
while (status == AVAssetWriterStatusUnknown) {
    NSLog(@"Waiting for video to complete...");
    [NSThread sleepForTimeInterval:0.5f];
    status = videoWriter.status;
}

NSLog(@"Video completed");

@synchronized(self) {
    success = [videoWriter finishWriting];
    NSLog(@"Success: %@", success);
    if (!success) {
        // We failed to successfully finalize the video file.
        NSLog(@"finishWriting returned NO");

    } else {
        // The video file was successfully written to the Documents folder.
        filePath = [[self getDocumentsFileURL:videoFileName] path];
        if (action == Save_Video_To_Album) {

            // Move the video to an accessible location on the device.
            NSLog(@"Temporary video filePath=%@", filePath);
            if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(filePath)) {
                NSLog(@"Video IS compatible. Adding it to photo album.");
                UISaveVideoAtPathToSavedPhotosAlbum(filePath, self, @selector(copyToPhotoAlbumCompleteFromVideo: didFinishSavingWithError: contextInfo:), nil);
            } else {
                NSLog(@"Video IS NOT compatible. Could not be added to the photo album.");
                success = NO;
            }
        } else if (action == Discard_Video) {
            NSLog(@"Video cancelled. Removing temporary video file: %@", filePath);
            [self removeFile:filePath];  
        }
    }

    [self cleanupWriter];
}

isRecording = false;

[pool drain];

return success; }

现在它在[videoWriter finishWriting]上崩溃了。我尝试添加[audioWriterInput markAsFinished]，但随后它就崩溃了。我会联系原始的海报，因为它似乎让它工作，但似乎没有办法发送私信。

有没有人对如何让它发挥作用或为什么会崩溃有任何建议？我已尽力解决这个问题，但我对Obj-C很新。如果需要，我可以发布其余代码（很多内容都在之前引用的原帖中）。

Answer 1

问题实际上可能出在writeAudioBuffer函数中。

如果您复制了该帖子中的代码但没有更改，那么您肯定会遇到一些问题。

你需要做这样的事情：

if ( ![self waitForAudioWriterReadiness]) {
    NSLog(@"WARNING: writeAudioBuffer dropped frame after wait limit reached.");
    return 0;
}

OSStatus status;
CMBlockBufferRef bbuf = NULL;
CMSampleBufferRef sbuf = NULL;

size_t buflen = n * nchans * sizeof(float);

CMBlockBufferRef tmp_bbuf = NULL;
status = CMBlockBufferCreateWithMemoryBlock(
                                            kCFAllocatorDefault, 
                                            samples, 
                                            buflen, 
                                            kCFAllocatorDefault, 
                                            NULL, 
                                            0, 
                                            buflen, 
                                            0, 
                                            &tmp_bbuf);

if (status != noErr || !tmp_bbuf) {
    NSLog(@"CMBlockBufferCreateWithMemoryBlock error");
    return -1;
}
// Copy the buffer so that we get a copy of the samples in memory.
// CMBlockBufferCreateWithMemoryBlock does not actually copy the data!
// 
status = CMBlockBufferCreateContiguous(kCFAllocatorDefault, tmp_bbuf, kCFAllocatorDefault, NULL, 0, buflen, kCMBlockBufferAlwaysCopyDataFlag, &bbuf);
//CFRelease(tmp_bbuf); // causes abort?!
if (status != noErr) {
    NSLog(@"CMBlockBufferCreateContiguous error");
    //CFRelease(bbuf);
    return -1;
}


CMTime timestamp = CMTimeMake(sample_position_, 44100);

status = CMAudioSampleBufferCreateWithPacketDescriptions(
    kCFAllocatorDefault, bbuf, TRUE, 0, NULL, audio_fmt_desc_, 1, timestamp, NULL, &sbuf);

sample_position_ += n;
if (status != noErr) {
    NSLog(@"CMSampleBufferCreate error");
    return -1;
}
BOOL r = [audioWriterInput appendSampleBuffer:sbuf];
if (!r) {
    NSLog(@"appendSampleBuffer error");
}
//CFRelease(bbuf); // crashes, don't know why..  Is there a leak here?
//CFRelease(sbuf);

return 0;

对于内存管理有一些事情我不确定。

另外请务必使用：

audioWriterInput.expectsMediaDataInRealTime = YES;

使用Obj-C插件和AVAssetWriterInput为视频添加音频

1 个答案: