M1 builds struggling playback with 4K HEVC content

[eXhumer]

I tried to playback the same video (4K HEVC) on both the Intel build and the native ARM build on Mac mini. Funnily enough, Intel build was able to playback the video without issue. The native ARM build however was experiencing stutters/grey screens/audio cutouts during playback. Both downloaded straight from VLC website. Is this software bug that needs to be fixed, or is this user error?

Intel Build Video Output


M1 Build Video Output

[fkuehne]

This is unexpected. Please provide media-info output for the sample file.

[eXhumer]

I excluded the subtitle stream information from the output as I was reaching the post character limit.

Code: Select all

General Unique ID : 56894977862465882574635961795040070247 (0x2ACD92FBD3697A576A3E7A8D4A8D4A67) Complete name : REDACTED.mkv Format : Matroska Format version : Version 4 File size : 4.13 GiB Duration : 36 min 14 s Overall bit rate : 16.3 Mb/s Encoded date : UTC 2020-08-21 06:38:26 Writing application : mkvmerge v48.0.0 ('Fortress Around Your Heart') 64-bit Writing library : libebml v1.4.0 + libmatroska v1.6.0 Video ID : 1 Format : HEVC Format/Info : High Efficiency Video Coding Format profile : Main 10@L5.1@Main Codec ID : V_MPEGH/ISO/HEVC Duration : 36 min 14 s Bit rate : 15.5 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 50.000 FPS Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 10 bits Bits/(Pixel*Frame) : 0.037 Stream size : 3.93 GiB (95%) Default : Yes Forced : No Color range : Limited Color primaries : BT.709 Transfer characteristics : BT.709 Matrix coefficients : BT.709 Audio ID : 2 Format : E-AC-3 JOC Format/Info : Enhanced AC-3 with Joint Object Coding Commercial name : Dolby Digital Plus with Dolby Atmos Codec ID : A_EAC3 Duration : 36 min 14 s Bit rate mode : Constant Bit rate : 768 kb/s Channel(s) : 6 channels Channel layout : L R C LFE Ls Rs Sampling rate : 48.0 kHz Frame rate : 31.250 FPS (1536 SPF) Compression mode : Lossy Stream size : 199 MiB (5%) Title : English [Original] Language : English Service kind : Complete Main Default : Yes Forced : No Complexity index : 16 Number of dynamic objects : 15 Bed channel count : 1 channel Bed channel configuration : LFE

[fkuehne]

Excellent, thanks for the details! I had to return the DTK last week so I'm without a M1 Mac for now to test myself.

Could you add a VLC debug log? To create, open the Messages panel from the Window menu before starting playback and then just save the output after playing a few frames with the distortion.

Thanks again!

[eXhumer]

Full log as requested with the filename of the playback file being replaced by REDACTED.
https://gist.github.com/eXhumer/e85a3bc ... e3ef41a901

[fkuehne]

OK, as I feared we fail to enable hardware decoding on the M1:

videotoolbox warning: unknown vt session error (-6)

This needs to be debugged with an actual M1 device.

Thank you for your help!