A question about h264 encoder

[Nuno Mota]

imx6 is capable of more than one hardware encoding at the same time...

* There is a limit for the number of pipelines which can be run
simultaneously, for high resolution input files, at most two for 1080p and
four for 720p.


2016-10-14 9:54 GMT+01:00 Thornton, Keith <keith.thornton at zeiss.com>:

> Hi, why do you not just encode once and then tee so that you can write to
> file on one branch and stream using the other branch. Do you need different
> sizes or framerates, or do you just need to puch the second branch through
> H264parse to recode it from avc to byte-stream
>
> Regards
>
> Keith
>
>
>
> *Von:* gstreamer-devel [mailto:gstreamer-devel-
> bounces at lists.freedesktop.org] *Im Auftrag von *??
> *Gesendet:* Donnerstag, 13. Oktober 2016 16:32
> *An:* Discussion of the development of and with GStreamer <
> gstreamer-devel at lists.freedesktop.org>
> *Betreff:* Re: A question about h264 encoder
>
>
>
> Actually, we need to use both the SW and HW encoder at the same time. And
> we want the SW encoder for streaming and HW encoder for storage.
>
> The SW encoder can have more options and parameters to control and change,
> especially for a low delay. That's why we want to use SW for real time
> streaming to client.
>
> The HW encoder will only be used for on board sd card storage of capture
> video.
>
>
>
> 2016-10-13 16:17 GMT+02:00 Tonu Jaansoo <tonu.jaansoo at gmail.com>:
>
> Why would you want to NOT use HW encoder, if it is available and working?
> As it was pointed out, CPU can't handle encoding the stream in realtime
> from source such as as a camera. (thats why there is HW encoder)
>
>
>
> Tõnu
>
>
>
> On 13 Oct 2016, at 14:58, 张若 <zr92zr at gmail.com> wrote:
>
>
>
> Anyway, thanks!
>
> But.. the board has both HW and SW 264 encoder on it. There is no problem
> to use x264enc.
>
> The problem is with videorate. If I use videorate and x264enc without
> setting drop-only as true, there will be problems while streaming. But that
> works fine without videorate, or works fine with using imxvpuenc_h264
> instead.
>
> I don't know why. I think that could be some problems with framerate,
> either with camera or encoder.
>
>
>
> 2016-10-13 14:26 GMT+02:00 Nuno Mota <mundumelga at gmail.com>:
>
> It is quite simple.
>
> imxvpuenc_h264 uses imx hardware encoder.
> x264enc uses the cpu, so It's software encoder. You wont be able to use it
> on an ARM CPU. Imx just cant handle it.
>
> Check "top" and you will se the cpu load/usage...
>
>
>
> On Oct 13, 2016 1:17 PM, "张若" <zr92zr at gmail.com> wrote:
>
> I found the solution myself. But still not understand the reason
> thoroughly.
>
>
>
> The problem is with the videorate, it needs to be set with drop-only=true,
> especially for the board. Otherwise, it seems to duplicate several frames
> and cause a large delay as well.
>
> But I still don't why does this happen? and why there is no problem while
> using imxvpuenc_h264?
>
>
>
> Hope somebody could explain that!
>
>
>
> Thanks!
>
>
>
>
>
>
>
> 2016-10-13 11:32 GMT+02:00 张若 <zr92zr at gmail.com>:
>
> Hi,
>
>
>
> I am working on the imx6 board. There are two h264/x264 encoder, HW
> encoder named imxvpuenc_h264 and SW encoder named x264enc. I tried both of
> them. But problem appears.
>
>
>
> The pipeline looks like this: (the video camera capture is 720p)
>
>
>
> imxv4l2videosrc -> capsfilter1 -> videoscale -> videorate -> videoconvert
> -> capsfilter2 -> imxvpuenc_h264 (or x264enc) -> queue -> h264parse ->
> mpegtsmux -> rtpmp2tpay -> udpsink
>
>
>
> While using imxvpuenc_h264, there is no large latency, but using x264enc
> will cause a really large latency (sometimes around 10s and frame stucks).
>
>
>
> When I set "capsfilter2" to lower resolution such as 320x240, the latency
> comes much shorter for x264enc. On the other hand, if I remove the
> "videoscale -> videorate -> videoconvert" part while using x264enc, there
> almost no latency for the streaming.
>
>
>
> For x264enc, I set "tune=zerolatency, key-int-max=32, bframes=0,
> speed-preset=1, bitrate=4000 (may changes from 1000 to 10000)".
>
>
>
> I don't know the reason why it happens and how can I deal with that.
> Please help!
>
>
>
> Thanks in advance!
>
>
>
>
>
>
>
>
>
>
>
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