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Specify start absolute timestamp to overlay

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marc lievens-3

Specify start absolute timestamp to overlay

Hi Gstreamer Guys,

Is there a way to specify the start absolute timestamp which has to be overlay while playing video from file.

I already did take a look with ClockOverlay, TimeOverlay and TextOverlay, but this doesn’t allow me start date time to use, or I missed something

I presume that this can be done somehow via a probe and add the date time on every frame while recording or playing the video.

But I presume that there are more easier ways to establish this.

Thanks for any tips.

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jackBuffington

Re: Specify start absolute timestamp to overlay

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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marc lievens-2

Re: Specify start absolute timestamp to overlay

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 <[hidden email]>:

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/
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel