Atem: Low encoder recording quality despite correct settings

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Screencaster

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  • Joined: Tue May 18, 2021 7:29 pm
  • Real Name: Jason Nerer

Atem: Low encoder recording quality despite correct settings

PostTue May 18, 2021 8:03 pm

Dear All,

I know it's an old topic, but I simple don't get ISO recording quality which is remotely acceptable.

My Setup:

- Atem Mini Pro ISO
- Lacie Portable SSD 1TB
- HDMI input signal (Macbook M1 -> CalDigit -> HDMI Splitter -> Atem)
- Atem Software Control 8.6.1
- Atem Firmware latest (updated as of today)

My Config:

I always configured the Quality Setting such, that the ISO recording quality should be up to 70MBit/s, so I chose one of the profiles and selected: "Quality: Hyperdeck High).

Image

The recorded ISO streams are ok'ish, but especially in darker regions left and right of the screen, I get horrible compression artifacts. When checking the bitrate with "mediainfo" it's always only about 5Mbit/s, way too low.

Then I read, that one can configure custom Encoding Profiles via the Streaming.xml. I copied a profile and configed 64MBit/s, 32MBit/s and 16MBit/s testwise.

Image

Still I have the same problem. Especially darker screens have compression artifacts like crazy, and there is a "pumping effect" in bigger, darker areas.

My Tests:

As a crosscheck I recorded the same scene via Quicktime screenrecorder. This file as well as the Atem's one have quite a similar bitrate.

Atem: 12,4MBit/s

Image

Quicktime: 11,6MBit/s

Image

Even though this bitrate should be absolutely sufficient for a still image and no movement on the screen, the Atem output quality is terrible.

Atem Screenshot:

Image

And the artifacts do not disappear. In contrast the same screenshot from the Quicktime recording which comes at a even lower bitrate.

Quicktime Screenshot:

Image

After days and days of reading / testing / failing I am desparate. If the program stream had these artifacts, fine. But the ISO files must not have them. But whatever I do, I do not even get ISO footage with more that 12MBit/s.

I bought the Atem so I would explicitly not have to put additional load on my CPU while creating a screencast. But this behaviour renders the Atem close to useless for semiprofessional productions. I can not imagine, that BM releases such a product, therefore I still believe (and hope) I made a mistake.

Btw, I do not believe, that its the harddrive:

Code: Select all
dd if=/dev/urandom of=testfile bs=1m count=1024
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 2.640095 secs (406705753 bytes/sec)


That's a whopping 387 MByte/s or 3102 MBit/s. Should be enough for 5 70MBit ISO Streams. And I am just recording one!

Can anyone confirm that issue? Can anyone help solving it? I would really like to like the Atem.

Regards
Screencaster

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