我正在学习Xuggler（一个库支持Java的视频流），遵循tutorial教学how to decode and play video中的代码。
我认为这段代码是可靠的，但是当我想在我的窗口上播放视频时，我收到错误告诉我
Exception in thread "main" java.lang.RuntimeException: got error decoding video in: C:/Users/swnmlab/1.mp4
此行执行时会发生此错误
int bytesDecoded = videoCoder.decodeVideo(picture, packet,offset);
我使用调试器进入并发现xuggle-xuggler.jar没有源附件，有没有人遇到过这个问题？
import java.awt.image.BufferedImage;
import com.xuggle.xuggler.ICodec.Type;
import com.xuggle.xuggler.IContainer;
import com.xuggle.xuggler.IPacket;
import com.xuggle.xuggler.IPixelFormat;
import com.xuggle.xuggler.IStream;
import com.xuggle.xuggler.IStreamCoder;
import com.xuggle.xuggler.IVideoPicture;
import com.xuggle.xuggler.IVideoResampler;
import com.xuggle.xuggler.Utils;
import com.xuggle.xuggler.demos.VideoImage;
public class DecodeAndPlayVideo {
public static void main(String[] args) {
String filename = "C:/Users/swnmlab/1.mp4";
// Create a Xuggler container object
IContainer container = IContainer.make();
// Open up the container
if (container.open(filename, IContainer.Type.READ, null) < 0)
throw new IllegalArgumentException("could not open file: "
+ filename);
// query how many streams the call to open found
int numStreams = container.getNumStreams();
// and iterate through the streams to find the first video stream
int videoStreamId = -1;
IStreamCoder videoCoder = null;
for (int i = 0; i < numStreams; i++) {
// Find the stream object
IStream stream = container.getStream(i);
// Get the pre-configured decoder that can decode this stream;
IStreamCoder coder = stream.getStreamCoder();
if (coder.getCodecType() == Type.CODEC_TYPE_VIDEO) {
videoStreamId = i;
videoCoder = coder;
break;
}
}
if (videoStreamId == -1)
throw new RuntimeException(
"could not find video stream in container: " + filename);
if (videoCoder.acquire() < 0)
throw new RuntimeException(
"could not open video decoder for container: " + filename);
IVideoResampler resampler = null;
if (videoCoder.getPixelType() != IPixelFormat.Type.BGR24) {
// if this stream is not in BGR24, we're going to need to
// convert it. The VideoResampler does that for us.
resampler = IVideoResampler.make(videoCoder.getWidth(),
videoCoder.getHeight(), IPixelFormat.Type.BGR24,
videoCoder.getWidth(), videoCoder.getHeight(),
videoCoder.getPixelType());
if (resampler == null)
throw new RuntimeException("could not create color space "
+ "resampler for: " + filename);
}
/*
* And once we have that, we draw a window on screen
*/
openJavaWindow();
IPacket packet = IPacket.make();
while (container.readNextPacket(packet) >= 0) {
/*
* Now we have a packet, let's see if it belongs to our video stream
*/
if (packet.getStreamIndex() == videoStreamId) {
IVideoPicture picture = IVideoPicture.make(
videoCoder.getPixelType(), videoCoder.getWidth(),
videoCoder.getHeight());
int offset = 0;
while (offset < packet.getSize()) {
/*
* Now, we decode the video, checking for any errors.
*/
int bytesDecoded = videoCoder.decodeVideo(picture, packet,
offset);
if (bytesDecoded < 0)
throw new RuntimeException(
"got error decoding video in: " + filename);
offset += bytesDecoded;
/*
* Some decoders will consume data in a packet, but will not
* be able to construct a full video picture yet. Therefore
* you should always check if you got a complete picture
* from the decoder
*/
if (picture.isComplete()) {
IVideoPicture newPic = picture;
/*
* If the resampler is not null, that means we didn't
* get the video in BGR24 format and need to convert it
* into BGR24 format.
*/
if (resampler != null) {
// we must resample
newPic = IVideoPicture.make(
resampler.getOutputPixelFormat(),
picture.getWidth(), picture.getHeight());
if (resampler.resample(newPic, picture) < 0)
throw new RuntimeException(
"could not resample video from: "
+ filename);
}
if (newPic.getPixelType() != IPixelFormat.Type.BGR24)
throw new RuntimeException("could not decode video"
+ " as BGR 24 bit data in: " + filename);
@SuppressWarnings("deprecation")
BufferedImage javaImage = Utils.videoPictureToImage(newPic);
// and display it on the Java Swing window
updateJavaWindow(javaImage);
}
}
} else {
/*
* This packet isn't part of our video stream, so we just silently drop it.
*/
do {
} while (false);
}
}
closeJavaWindow();
}
private static VideoImage mScreen = null;
private static void updateJavaWindow(BufferedImage javaImage) {
mScreen.setImage(javaImage);
}
private static void openJavaWindow() {
mScreen = new VideoImage();
}
private static void closeJavaWindow() {
System.exit(0);
}
}
P.S。如果您想尝试使用此库，可以找到安装文件here，然后按照this page上的步骤完成在Windows上安装此库。
我发现错误发生是因为我改变了原始代码
if (videoCoder.open() < 0)
throw new RuntimeException(
"could not open video decoder for container: " + filename);
到
if (videoCoder.acquire() < 0)
throw new RuntimeException(
"could not open video decoder for container: " + filename);
因为open（）方法导致弃用警告，所以我使用auto complete来查找看起来像open（）的方法，然后改为acquire（）。我认为没关系，因为没有“无法打开容器的视频解码器：”异常被抛出。所以只需按照示例代码。
答案 0 :(得分：4)
open（）方法，你应该使用open（null，null）代替
if (videoCoder.open(null,null) < 0)
throw new RuntimeException(
"could not open video decoder for container: "
+ filename);
答案 1 :(得分：2)
我查看了您的代码，发现您获得了videoCoder，但在播放之前您没有open。也许这就是为什么你无法解码它。你能试一试吗？
if (videoCoder.open() < 0)
throw new RuntimeException(
"could not open video decoder for container: "
+ filename);
IVideoResampler resampler = null;
答案 2 :(得分：1)
我执行了相同的代码并进行了以下代码更改。需要进行这些更改，因为以下API已弃用。
IMetaData params = IMetaData.make();
IContainerParameters params = IContainerParameters.make();
如图所示，我使用videoCoder设置timeBase，Height和Width。
if (coder.getCodecType() == ICodec.Type.CODEC_TYPE_VIDEO)
{
videoStreamId = i;
videoCoder = coder;
// The timebase here is used as the camera frame rate
videoCoder.setTimeBase(IRational.make(30,1));
// we need to tell the driver what video with and height to use
videoCoder.setWidth(320);
videoCoder.setHeight(240);
break;
}
但是，我面临着一个不同的问题，即网络摄像头显示占据整个屏幕，而不是指定的宽度和高度。
代码更改是否设置高度和宽度不正确？我们该如何控制尺寸？