HEVC glitches with AML decoder

Development Development & Testing
1

Hello,

some DVB-T2/HEVC live TV streams are not decoded properly with AML HW decoder (Amlogic S912). Flickering and pixelating begins during playback or when switching to a channel. After some time it will repair itself.

Samples and logs: https://drive.google.com/open?id=1zu77fcKilF14_SEBPKYfYPlw29gJpLSf

  1. sample1.ts: auto fixed at 00:32
  2. sample2.ts: From the beginning, the whole is decoded correctly, but after skipping anywhere after 0:15 there are glitches.
2

In CoreELEC settings, enable the HEVC workaround and reboot, then try again.

3

No change with HEVC seek workaround.

4

This is really strange h265 encoding, even in PC (VLC or MPC) has issue to play smoothly. The issue is in kernel hw decoding. I tried play them in 4.9 kernel (Odroid N2), perfect smooth, no glitches. You have to wait for kernel upgrade.

5

@afl: You’re right. Glitches are caused by a broken kernel (3.14) module vh265 or its microcode when initial POC is calculated negative. Once it exceeds 0, it’s better.

But there are more bugs in the HEVC decoder - occasionally image freezing and decoder resets during live TV streams.

6

Identical glitches occur on the S905X3 from version 9.2.6 (Amlogic-ng, H.265 hardware decoder). S905X3 device with CoreELEC ng 9.2.5 and older plays attached sample video smoothly. Seems broken since 28 Nov 2020 commits 5b6cc03 / 32af77e coreelec-9.2 branch.

Sample video: https://drive.google.com/file/d/1Azcfj2Ph_1ZcfbUNZOVHU3xLlCzHkzSf/view?usp=sharing

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