HEVC glitches with AML decoder


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.

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

No change with HEVC seek workaround.

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.

@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.

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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