Hi,<br><br>yes, I DO hate the default gmail settings..<br><br><div class="gmail_quote">---------- Forwarded message ----------<br>From: <b class="gmail_sendername">Marco Ballesio</b> <span dir="ltr"><<a href="mailto:gibrovacco@gmail.com">gibrovacco@gmail.com</a>></span><br>
Date: Sat, Sep 18, 2010 at 4:52 PM<br>Subject: Re: [gst-embedded] gstreamer dma buffer & management<br>To: Feng Ye <<a href="mailto:fye@broadcom.com">fye@broadcom.com</a>><br><br><br>Hi,<br><br><div class="gmail_quote">
<div class="im">On Fri, Sep 17, 2010 at 2:49 AM, Feng Ye <span dir="ltr"><<a href="mailto:fye@broadcom.com" target="_blank">fye@broadcom.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hello there,<br>
<br>
I am working on a video dec plugin (based on hardware dec). I plan to use filesrc to read a raw H264 file and feed to my plugin.<br></blockquote></div><div><br>it's generically better to use a container format rather than a raw h264 byte-stream. If a container is not an option for your case, maybe you could use at least an annex-B compliant stream. This makes it easier to identify NAL boundaries. It should anyway possible to use even an unformatted NAL sequence (see below).<br>
</div><div class="im"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
The buffers from plugin's sink pad are the source data for decoding so they need to be DMA-able. Is there way to control how the buffers are allocated? Since they are allocated in filesrc so that's not possible? Looks like I will need to allocate my own buffer in my plugin and then copy them over?<br>
</blockquote></div><div><br>if you're not using any container format, the source has no way to pass to you buffers aligned with NAL boundaries, so you definitely need an adapter somewhere (see below).<br> </div><div class="im">
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
Also, a video frame may contain less bytes than what's in the buffer, what do I do with the remaining bytes?<br>
>From the ffmpeg example (they are software based so the first dma question does not exist), they create a sub buffer of the remaining bytes and then does a buffer join. These are time consuming I think. </blockquote>
</div><div><br>yes it is, but I guess you could afford it for compressed data. The overhead depends, of course, on the bandwidth you're using.<br> </div><div class="im"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
I wonder if there are other faster solution? One thing I think might help is to have another plugin in between, which parse the file and only give one frame size of data to my plugin. But I am not sure if these kind of plugin exists.<br>
</blockquote></div><div><br>You can use h264parse for this. It will identify NAL boundaries and pass them to your plugin on separated buffers. Btw everything has a price and in this case it's the penalty like described some rows above.<br>
<br>Regards.<br> </div><div class="im"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
<br>
Thanks,<br>
Feng<br>
<br>
<br>
<br>
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