This article describes code for an HTTP provider that enables generation of a thumbnail image from a live stream without the need for the live stream to be the source of a Transcoder session. The HTTP provider uses an API that enables decoding and scaling of key frames using the decoder portion of the Transcoder.
Note: Wowza Streaming Engine™ 4.5.0 or later is required.
The code sample that uses the API is:
ThumbnailerRequest request = new ThumbnailerRequest(stream, width, height, fitMode); request.addPacket(keyFrame); ThumbnailerResponse response = ThumbnailerUtils.generateThumbnail(vhost, request);
The thumbnail image is returned as an RGBA byte array. This byte array can then be converted to a Java BufferedImage using the ThumbnailerUtils.nativeImageToBufferedImage(response); utility method. The following example code uses this API to convert the result to JPEG or PNG data:
BufferedImage image = ThumbnailerUtils.nativeImageToBufferedImage(response);
if (image != null)
{
WMSLoggerFactory.getLogger(CLASS).info(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"]: Image result: format:"+formatStr+" size:"+image.getWidth()+"x"+image.getHeight());
try
{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, formatStr.equals("jpeg")?"jpg":formatStr, baos);
synchronized(this)
{
outBytes = baos.toByteArray();
}
}
catch(Exception e)
{
WMSLoggerFactory.getLogger(CLASS).error(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"] ", e);
}
}
The following is the full source for an example HTTP provider that used this API:
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;
import com.wowza.util.*;
import com.wowza.wms.amf.*;
import com.wowza.wms.application.*;
import com.wowza.wms.http.*;
import com.wowza.wms.logging.*;
import com.wowza.wms.stream.*;
import com.wowza.wms.transcoder.httpprovider.*;
import com.wowza.wms.transcoder.model.*;
import com.wowza.wms.transcoder.util.*;
import com.wowza.wms.vhost.*;
public class HTTPProviderGenerateThumbnail extends HTTProvider2Base
{
private static final Class<HTTPProviderGenerateThumbnail> CLASS = HTTPProviderGenerateThumbnail.class;
private static final String CLASSNAME = "HTTPProviderGenerateThumbnail";
public void onHTTPRequest(IVHost vhost, IHTTPRequest req, IHTTPResponse resp)
{
if (!doHTTPAuthentication(vhost, req, resp))
return;
byte[] outBytes = null;
String formatStr = "jpeg";
String fitModeStr = "letterbox";
String cropStr = null;
int[] crop = null;
try
{
while(true)
{
String queryStr = req.getQueryString();
if (queryStr == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest: Query string missing");
break;
}
Map<String, String> queryMap = HTTPUtils.splitQueryStr(queryStr);
String streamName = queryMap.get("streamname");
if (streamName == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest: Streamname not specified");
break;
}
String comboAppStr = queryMap.get("application");
if (comboAppStr == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest: Application name not specified");
break;
}
if (queryMap.containsKey("fitmode"))
fitModeStr = queryMap.get("fitmode");
if (queryMap.containsKey("fitMode"))
fitModeStr = queryMap.get("fitmode");
if (queryMap.containsKey("format"))
formatStr = queryMap.get("format");
if (formatStr == null)
formatStr = "jpeg";
formatStr = formatStr.trim().toLowerCase();
if (formatStr.equals("jpg"))
formatStr = "jpeg";
String sizeStr = queryMap.get("size");
int width = 0;
int height = 0;
if (sizeStr != null)
{
int cindex = sizeStr.indexOf("x");
try
{
width = Integer.parseInt(sizeStr.substring(0, cindex));
height = Integer.parseInt(sizeStr.substring(cindex+1));
}
catch(Exception e)
{
}
}
if (queryMap.containsKey("crop"))
cropStr = queryMap.get("crop");
if (cropStr != null)
{
String[] parts = cropStr.split(",");
if (parts.length >= 4)
{
crop = new int[4];
for(int i=0;i<4;i++)
{
int cropVal = -1;
try
{
cropVal = Integer.parseInt(parts[i].trim());
}
catch(Exception e)
{
}
if (cropVal > 0)
{
crop[i] = cropVal;
}
}
}
}
String applicationStr = comboAppStr;
String appInstanceStr = IApplicationInstance.DEFAULT_APPINSTANCE_NAME;
int cindex = applicationStr.indexOf("/");
if (cindex > 0)
{
appInstanceStr = applicationStr.substring(cindex+1);
applicationStr = applicationStr.substring(0, cindex);
}
IApplication applicationLoc = vhost.getApplication(applicationStr);
if (applicationLoc == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest: Application could not be loaded: "+applicationStr);
break;
}
IApplicationInstance appInstance = applicationLoc.getAppInstance(appInstanceStr);
if (appInstance == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest: Application instance could not be loaded: "+applicationStr+"/"+appInstanceStr);
break;
}
IMediaStream stream = appInstance.getStreams().getStream(streamName);
if (stream == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"]: Stream not found: "+streamName);
break;
}
AMFPacket keyFrame = stream.getLastKeyFrame();
if (keyFrame == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"]: No key frame");
break;
}
int fitmode = TranscoderStreamUtils.frameSizeFitModeToId(fitModeStr);
if (fitmode <= 0)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"]: Fit mode not recognized defaulting to letterbox: "+fitModeStr);
fitmode = TranscoderStream.FRAMESIZE_FITMODE_LETTERBOX;
}
ThumbnailerRequest request = new ThumbnailerRequest(stream, width, height, fitmode);
request.addPacket(keyFrame);
if (crop != null)
request.setCrop(crop);
ThumbnailerResponse response = ThumbnailerUtils.generateThumbnail(vhost, request);
if (response == null)
{
WMSLoggerFactory.getLogger(CLASS).warn(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"]: Thumbnail generation failed");
break;
}
BufferedImage image = ThumbnailerUtils.nativeImageToBufferedImage(response);
if (image != null)
{
WMSLoggerFactory.getLogger(CLASS).info(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"]: Image result: format:"+formatStr+" size:"+image.getWidth()+"x"+image.getHeight());
try
{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, formatStr.equals("jpeg")?"jpg":formatStr, baos);
synchronized(this)
{
outBytes = baos.toByteArray();
}
}
catch(Exception e)
{
WMSLoggerFactory.getLogger(CLASS).error(CLASSNAME+".onHTTPRequest["+applicationStr+"/"+appInstanceStr+"/"+streamName+"] ", e);
}
}
break;
}
}
catch (Exception e)
{
WMSLoggerFactory.getLogger(HTTPTranscoderThumbnail.class).error("HTTPTranscoderThumbnail ", e);
}
try
{
if (outBytes != null)
{
resp.setHeader("Content-Type", "image/"+formatStr);
OutputStream out = resp.getOutputStream();
out.write(outBytes);
}
else
resp.setResponseCode(404);
}
catch (Exception e)
{
WMSLoggerFactory.getLogger(HTTPTranscoderThumbnail.class).error("HTTPTranscoderThumbnail ", e);
}
}
}
The above HTTP provider is built into Wowza Streaming Engine and can be used by adding the following HTTP provider definition to the [install-dir]/conf/VHost.xml file. Add it as the second-to-last entry in the HostPort configuration for port 8086 (admin) port:
<HTTPProvider> <BaseClass>com.wowza.wms.transcoder.thumbnailer.HTTPProviderGenerateThumbnail</BaseClass> <RequestFilters>thumbnail*</RequestFilters> <AuthenticationMethod>none</AuthenticationMethod> </HTTPProvider>
The URL format is:
http://[wowza-ip-address]:8086/thumbnail?application=[application-name]&streamname=[stream-name]&size=[width]x[height]&fitmode=[fitmode]&crop=[left],[right],[top],[bottom]&format=[png,jpg]
- application: Application name (required).
- streamname: Stream name (required).
- size: Thumbnail size in pixels (required).
- fitmode: Fit mode (how video frame is fit to frame size). Valid values are letterbox, stretch, fit-height, fit-width, match-source, crop (default is letterbox).
- crop: Number of pixels to crop from source image.
- format: Format of the image. Valid values are jpeg and png (default is jpeg).
Example:
http://[wowza-ip-address]:8086/thumbnail?application=live&streamname=myStream&size=640x360&fitmode=letterbox
