Hello everyone,
It looks like we have an issue with audio drops/silences/glitches at hdmi out
with encoder at 1080P60 and HDMI source at 1080P60 playing 1080P25 movies.
…no problem with encoder down to 30…
Any ideas pls ?
Thanks in advance
Hello,
This is not necessarily something we have heard of before, are the audio drop outs occurring in recordings/streams, or just on the HDMI output? I’m assuming the source is a computer playing a 25fps video file with embedded HDMI audio? Have you tried a different source?
One thing to note here is that there is no real advantage to encoding at 60FPS if the source is 25 or 30FPS. This is because the Pearl is not an “upscaler” in the sense that it will create new intermediate frames to go from 25 to 60, it will simply duplicate the existing frames to match the new framerate. So if using 30fps for the encoding works to resolve the situation then this could be a reasonable work-around potentially.
If you’d like to troubleshoot further we could potentially test this in our lab to try and replicate the issue, we would need you send in an email to info@epiphan.com so we can open a support ticket.
Hello Adam,
So to be precise, I used the HDMI output of my Laptop (Dell 7510) to fead the Nano HDMI input and I’ve enabled audio from HDMI in and put encoder at 60
I put display parameters on duplicated mode and at 1920x1080 60 (or 59.94 maybe don’t remember) for both screens,
and I watched a BMD Video Assist 7"12G feaded by the HDMI out of the Nano (not tried loop) to check, with Channel selected
with youtube videos no problem, I’v just putted ±200ms of delay to be ±sync,
then I’ve tried to play some movies trailers (standards like 1280x720 at 25 with AC-3 audio at 48khz/16bits) from my computer with VLC,
and while this, a rythm blank serie “appeared” on my headphone, along the movie. I’ve bypassed Nano to check and audio was clear.
Then I moved encoder frame rate to 50 and then 30, and at 30 audio was back ok.
I perfectly understand your talking about ‘no advantage’ about transcoding up but you could admit that most PC today
can easily manage 1080P60 (or even more and more UHD, most 30 at this time maybe…) and this format is now usual at CDN streams and video files.
And the use case I feed you back is an everyday one.
Nevertheless your infos on “how” is it treated by Nano is maybe an interresting lead about this “audio drop” case.
I’ve keep the SD card of my test, there should be some records on it, anyway to cath them by with a simple computer ?
I can send the movies too.
Thanks in advance.
BR.
Thanks for the additional clarification BR! Please go ahead and send in the recordings to info@epiphan.com if they also present the same issue. They are standard MP4 files encoded in H.264 and are playable by any media player, VLC for example.
You can also view the recordings within the Pearl web interface itself. Simply navigate to the recordings page under the channel and you will see your recorded files with a triangle “Play” button next to them. Clicking that button will open a browser based video player.
If the recordings don’t present the issue, then we can focus on the HDMI output/connected device and on that note I have a few suggestions for things to try:
- Try a different connected device/monitor with audio capability/speakers on the HDMI output, such as a standard TV, just to rule out any compatibility issues with the BMD Video Assist specifically.
- Try the pass-through HDMI out vs the Program HDMI output.
- If using the program HDMI output, try changing the following settings:
- Under “Source”, try the channel vs the actual HDMI input or vice versa
- Under “Resolution” try the 3 options, i.e. “same as source”, “destination default” and 1920 x 1080
One other thing to check here would be overall system performance. Encoding at 60fps uses twice the processing of 30, and if there is a lot of scaling or cropping being used in the layout this could have an adverse effect on performance.
You can check this by going to the “Info” page of the web interface and looking at the “Target” vs “Actual” frame rate. If the actual is below the target then this would be an indication that the system is overloaded and could certainly result in audio drop outs. This would also be present on the recording so checking those will be a very good indicator of where this issue lies.
Hello Adam,
Thanks you a lot for all your advice but we don’t have Nano anymore, it’s gone back to our supplier FVS(fr).
And I only still have the SD card I used with it, with some record on it
How can we “recover” the files from this with a simple computer ?
DC.
The recorded files are simply in a Linux file format, there are many free programs available which will allow you to read/download them if you’re using a windows computer.
Great, I will check this out.
If any records are revelant I’ll send them…
Thx.