[gst-embedded] Need Help On gst-omapfb built from openembedded

[Arnout Vandecappelle]

 omapfbsink requires a chunk of memory that is accessible by the video 
hardware.  It allocates one of those in omapfbsink->buffer.  It also has a 
specific buffer_alloc function, so that upstream elements can write directly 
into this memory area.

 If the memcpy is still taking place (have you verified that it is?), it 
means that the upstream element is not using the buffer_alloc function.  I 
can think of two things that could go wrong.

- The upstream element is a queue: because of the queue, more than one 
buffer will be allocated by the upstream element.  However, the omapfbsink 
has only one hardware-accelerated buffer, so the other ones will use a 
normal malloc.

- The upstream element is something like a TIViddec.  Although these 
elements are supposed to accelerate the video encoding/decoding, the 
implementation is slightly braindead and introduces a lot of memcpy's.  More 
specifically, it allocates a hardware-accelerated buffer itself, but 
omapfbsink doesn't understand that it's hardware-accelerated so goes on 
memcpy-ing.


 In this particular case, I think there's an easy work-around.  (Warning: I 
haven't verified that this will work!)  The only constraint that the video 
hardware really has is that the buffer must be aligned at a 32-byte 
boundary, IIRC.  So, you can replace the condition

if(data != omapfbsink->buffer && ...)

with

if ((data & 0x1F) != 0)  /* Must be aligned on 32-byte boundary */

to make sure the memcpy is only done if it's not already aligned.  Then, use 
the patch in https://bugzilla.gnome.org/show_bug.cgi?id=596832 to make sure 
that most allocations are aligned (configure gstreamer core with --with-
buffer-alignment=32).


 Let me know if this helps :-)

 Regards,
 Arnout

On Saturday 27 March 2010 10:33:48, Tejas wrote:
> Hello All,
> 
>                Is it possible to pass decoder output buffer directly to
> color conversion routine. The snap shot of render function is as
> followed.
> 
> 
> 
> static GstFlowReturn
> 
> render (GstBaseSink * bsink, GstBuffer * buf)
> 
> {
> 
>     int i, w, h;
> 
>     GstOmapFbSink *omapfbsink = GST_OMAPFB_SINK(bsink);
> 
>     __uint8_t *fb = omapfbsink->framebuffer, *data =
> GST_BUFFER_DATA(buf);
> 
>        long iTime=0;
> 
>    struct timeval tempo1, tempo2;
> 
> 
> 
>     if(omapfbsink->plane_info.enabled == 2)
> 
>     {
> 
>         omapfbsink->plane_info.enabled = 1;
> 
> 
> 
>         g_mutex_lock (omapfbsink->x_lock);
> 
>         gst_omapfbsink_update_plane(omapfbsink);
> 
>         g_mutex_unlock (omapfbsink->x_lock);
> 
>     }
> 
> 
> 
>     g_print("\n Address in render function = %x\n", (unsigned
> int)GST_BUFFER_DATA(buf));
> 
>     /* If a buffer which wasn't supplied by us is given to us to render
> with,
> 
>        we need to copy to our buffer first so that memory alignment
> constraints
> 
>        are met. */
> 
> 
> 
>     if(data != omapfbsink->buffer && GST_BUFFER_SIZE(buf) <=
> omapfbsink->buffer_size)
> 
>     {
> 
>         memcpy(omapfbsink->buffer, data, GST_BUFFER_SIZE(buf));
> 
>         data = omapfbsink->buffer;
> 
>     }
> 
> 
> 
>     /* buffer_alloc gave a direct buffer, so we have nothing to
> 
>        do here... */
> 
>     if(omapfbsink->row_skip)
> 
>         return GST_FLOW_OK;
> 
> 
> 
>     switch(omapfbsink->image_format) {
> 
>         case GST_MAKE_FOURCC('I', '4', '2', '0'):
> 
>             /* Convert to YUV422 and send to FB */
> 
> 
> 
>             h = GST_VIDEO_SINK_HEIGHT (omapfbsink);
> 
>             w = GST_VIDEO_SINK_WIDTH (omapfbsink);
> 
> 
> 
>             __uint8_t *y, *u, *v;
> 
>             y = data;
> 
>             u = y + w * h;
> 
>             v = u + w / 2 * h / 2;
> 
> 
> 
>             yuv420_to_yuv422(fb, y, u, v, w & ~15, h, w, w / 2,
> omapfbsink->fixinfo.line_length);
> 
>             break;
> 
> 
> 
>         case GST_MAKE_FOURCC('U', 'Y', 'V', 'Y'):
> 
>             /* Send to FB, taking into account line_length */
> 
> 
> 
>             w = 2 * GST_VIDEO_SINK_WIDTH (omapfbsink);
> 
>             for(i = 0; i < GST_VIDEO_SINK_HEIGHT (omapfbsink); i++)
> 
>             {
> 
>                 memcpy(fb, data, w);
> 
> 
> 
>                 fb += omapfbsink->fixinfo.line_length;
> 
>                 data += w;
> 
>             }
> 
> 
> 
>             break;
> 
>     }
> 
> 
> 
>     return GST_FLOW_OK;
> 
> }
> 
>                Here buf which is passed is my decoder output buffer
> having size = (width * height *1.5). I would like to replace memcpy
> seprated by blue color in above function. Is there any possibility to
> assign buf pointer directly to Y pointer which later go to color
> conversion.
> 
> 
> 
>                I am laking of some understanding of buffer_alloc of base
> sink. If any where I am wrong please correct me and try to guide me in
> right direction. In other way I was thinking to use dma transfer, but I
> am completely new for dma and will take much time to understand and
> write transfer function. If I can get some other solution, will be
> helpful in my project.
> 
> 
> 
> -Tejas.
> 
> 
> 
> 
> 
> From: Tejas [mailto:tejas at picus.in]
> Sent: Friday, March 26, 2010 3:33 PM
> To: 'gstreamer-embedded at lists.sourceforge.net'
> Subject: Need Help On gst-omapfb built from openembedded
> 
> 
> 
> Hello All,
> 
>                I am using gst-omapfb plugin built from openembedded which
> contains X-overlay patch on normal omapfb plugin as my video sink. My
> normal pipeline is as followed.
> 
> 
> 
> 
> 
> $gst-launch-0.10 filesrc location=1.mp4 ! myparser ! mydecoder !
> omapfbsink.
> 
> 
> 
> Src pad of my decoder is set as following caps .
> 
> 
> 
> ("video/x-raw-yuv",
> 
>  "width", G_TYPE_INT, mpeg4dec->info.width,
> 
> "height", G_TYPE_INT, mpeg4dec->info.height,
> 
> "framerate", GST_TYPE_FRACTION, mpeg4dec->fps_nu, mpeg4dec->fps_de,
> 
> "format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'),
> 
> "pixel-aspect-ratio", GST_TYPE_FRACTION,1,1,i NULL);
> 
> 
> 
>                Omapfbsink will accept I420 format and convert it to UYVY
> format  and copy it to frame buffer. In these all process it is using
> memcpy which copy data from buffer pushed from my decoder to buffer
> allocated locally. Here in omapfbsink memcpy is time consuming. Instead
> of using memcpy I would like to use some other method. But I am getting
> how can I replace memcpy.
> 
> 
> 
>                If anyone can guide me to replace memcpy, I will be
> pleasure for me.
> 
> 
> 
> 
> 
> -Tejas.

-- 
Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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