Specify start absolute timestamp to overlay

[marc lievens]

Hi,

Thanks for the info.
Seems not easy at first glance, but I'm certain going to try this.





Op di 4 feb. 2020 om 00:43 schreef jackBuffington <jbuffington at redzone.com>:

> You could do it with custom element if you are up for it.  I'm timestamping
> my video using a custom element but am doing it with binary code as small
> as
> possible so that I can do machine vision stuff later.  In short I am
> working
> off of the GstBaseTransform template provide by:
> https://gstreamer.mazdermind.de/
>
> I've implemented a transform function rather than a transform_ip function.
> I think that it should be possible to use transform_ip but I couldn't get
> it
> to work.    I've attached some code.  It doesn't do exactly what you want
> but should be a good starting point.
>
>
>
>
> // Here is where the input buffer is manipulated and copied to the output
> buffer(s)
> static GstFlowReturn gst_lfselement_transform (GstBaseTransform *trans,
> GstBuffer *inbuf, GstBuffer *outbuf)
> {
>
>         GstMapInfo inMap, outMap;
>         guint8 *dest;
>         guint8 *src;
>         static int frameCount = 0;
>         static int lastSeconds = 0;
>
>         gsize maxsize;
>         gsize inSize = gst_buffer_get_sizes (inbuf, NULL , &maxsize);
>         //~ g_print ( " In buf: \n " );
>         //~ g_print ( " In size:%lu " G_GSIZE_FORMAT " \n " , inSize);
>         //~ g_print ( " In maxsize:%lu " G_GSIZE_FORMAT " \n " , maxsize);
>         //~ g_print ( " In number of buffers: %u \n " , gst_buffer_n_memory
> (inbuf));
>
>
>         //~ gsize outSize = gst_buffer_get_sizes (outbuf, NULL , &maxsize);
>         //~ g_print ( " Out buf: \n " );
>         //~ g_print ( " Out size:%lu " G_GSIZE_FORMAT " \n " , outSize);
>         //~ g_print ( " Out maxsize:%lu " G_GSIZE_FORMAT " \n " , maxsize);
>         //~ g_print ( " Out number of buffers: %u \n " ,
> gst_buffer_n_memory
> (outbuf));
>
>
>
>         // map the input buffer
>         if (!gst_buffer_map (inbuf, &inMap, GST_MAP_READ))
>         {
>                 GST_WARNING_OBJECT (trans, "Could not map input buffer,
> skipping");
>                 return GST_FLOW_OK;
>         }
>
>         // map the output buffer
>         if (!gst_buffer_map (outbuf, &outMap, GST_MAP_WRITE))
>         {
>                 gst_buffer_unmap (inbuf, &inMap);
>                 GST_WARNING_OBJECT (trans, "Could not map output buffer,
> skipping");
>                 return GST_FLOW_OK;
>         }
>
>         dest = outMap.data;
>         src = inMap.data;
>
>
>         // Here's the do-nothing part.  It simply copies the buffer.
>         copyBuffer(src, dest, inSize);
>
>
>
>         // Here is the do-something part.
>         GstLfselement *lfselement = GST_LFSELEMENT (trans);
>
>
>         // encode some data onto the bottom of the screen.
>         time_t now = time(NULL);
>         struct tm currentTime = *localtime(&now);
>
>         struct timeval curTime;
>         gettimeofday(&curTime, NULL);
>         int milli = curTime.tv_usec / 1000;
>         uint8_t milliHigh = milli / 256;
>         uint8_t milliLow = milli % 256;
>
>         uint8_t timeStamp[5] = {currentTime.tm_hour, currentTime.tm_min,
> currentTime.tm_sec, milliHigh, milliLow};
>         encodeData(dest, 0, 478, lfselement->outInfo.width, timeStamp, 5);
>
>
>         // Tidy up
>         gst_buffer_unmap (outbuf, &outMap);
>         gst_buffer_unmap (inbuf, &inMap);
>         return GST_FLOW_OK;
>
> }
>
>
>
> static void copyBuffer(guint8 *inBuffer, guint8 *outBuffer, int bufferSize)
> {
>   // Copies each byte from the input buffer into the output buffer
>   // TODO:  This could probably be faster by using 64-bit variables.
>
>   guint8 *inPtr = (guint8*) inBuffer;
>   guint8 *inEnd = inPtr + (bufferSize);
>
>   do
>   {
>     *outBuffer++ = *inPtr++;
>   }
>   while (inPtr < inEnd - 1);
> }
>
>
>
>
> static void inline setPixel(guint8 *buffer, int X, int Y, int value, int
> width)
> {       /* Sets the pixel at that location to the given value
>         X and Y are the location of the pixel that I want to set.
>         width and height are the dimensions of the image.
>
>         UYVY data is formatted in groups of two pixels per UYVY grouping.
>         Think of it like this U (Y1) V (Y2)  where
>         Pixel 1 is Y1, U, V
>         Pixel 2 is Y2, U, V
>         U and V are sampled on every other column but are sampled on every
> row.
>
>         ### IT IS UP TO THE USER TO NOT SPECIFY A PIXEL LOCATION OUTSIDE
> OF     ###
>         ### THE BOUNDS OF THE BUFFER!
>                                                              ###
>         */
>
>         // Calculate the location in the buffer where the pixel should be
> set
>         int rowOffset = Y * width * 2;
>         int blockOffset = (X/2) * 2;
>         int whichY = X % 2; // this is which Y in the block that this
> corresponds
> to
>
>         int offset = rowOffset + blockOffset; // this is the location of
> the
> beginning of the UYVY block
>
>         buffer += offset;
>         *buffer = 128;                  // U
>         *(buffer + 2) = 128;   // Y
>         if(whichY)
>                 *(buffer + 3) = value;
>         else
>                 *(buffer + 1) = value;
> }
>
>
>
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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>
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