public IplImage grab() throws Exception {
if (pFormatCtx == null || pFormatCtx.isNull()) {
throw new Exception("Could not grab: No AVFormatContext. (Has start() been called?)");
}
boolean done = false;
long pts = 0;
while (!done) {
if (av_read_frame(pFormatCtx, packet) < 0) {
// throw new Exception("Could not read frame");
return null; // end of file?
}
// Is this a packet from the video stream?
if (packet.stream_index() == videoStream) {
// Decode video frame
int len = avcodec_decode_video2(pCodecCtx, pFrame, frameFinished, packet);
LongPointer opaque = new LongPointer(pFrame.opaque());
if (packet.dts() != AV_NOPTS_VALUE) {
pts = packet.dts();
} else if (!opaque.isNull() && opaque.get() != AV_NOPTS_VALUE) {
pts = opaque.get();
} else {
pts = 0;
}
AVRational time_base = pStream.time_base();
pts = 1000 * pts * time_base.num() / time_base.den();
// Did we get a video frame?
if (len > 0 && frameFinished[0] != 0) {
switch (colorMode) {
case BGR:
case GRAY:
// Deinterlace Picture
if (deinterlace) {
avpicture_deinterlace(
pFrame, pFrame, pCodecCtx.pix_fmt(), pCodecCtx.width(), pCodecCtx.height());
}
// Convert the image from its native format to RGB
sws_scale(
img_convert_ctx,
new PointerPointer(pFrame),
pFrame.linesize(),
0,
pCodecCtx.height(),
new PointerPointer(pFrameRGB),
pFrameRGB.linesize());
return_image.imageData(buffer);
return_image.widthStep(pFrameRGB.linesize(0));
break;
case RAW:
assert (pCodecCtx.width() == return_image.width()
&& pCodecCtx.height() == return_image.height());
return_image.imageData(pFrame.data(0));
return_image.widthStep(pFrame.linesize(0));
break;
default:
assert (false);
}
return_image.imageSize(return_image.height() * return_image.widthStep());
done = true;
}
}
// Free the packet that was allocated by av_read_frame
av_free_packet(packet);
}
return_image.timestamp = pts;
return return_image;
}
