Strange buffering/caching problems on Ugoos AM6b+

dmesg output: hastebin

Debug log: hastebin

When playing back the “Misbehaving.mp4” file, playback starts normally. If I seek ahead… cache seems to choke and playback basically stops completely or it takes a while to start, starts and then stops again, not to resume.

The file sits on Google Drive, mounted in a directory through rclone. Bandwidth is full gigabit, I have no problem streaming it from a PC connected to the same network.

I have tried several caching settings but the test (and above debug log) happened with
Buffer Mode: Buffer all filesystems, including local files
Memory Size: 256 MB
Read Factor: 50 x
Chunk Size : 1MB

When I started noticing the problem, read factor was set to Adaptive but it made no difference…

MediaInfo for the file:

Complete name                            : Misbehaving.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (isom/mp42/dby1)
File size                                : 5.05 GiB
Duration                                 : 28 min 44 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 25.2 Mb/s
Frame rate                               : 23.976 FPS
Encoded date                             : 2021-09-08 03:08:35 UTC
Tagged date                              : 2021-09-08 03:08:35 UTC
Writing application                      : GPAC-1.1.0-DEV-rev1011-ge57ff5682-master

ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5@High
HDR format                               : Dolby Vision, Version 1.0, Profile 5, dvhe.05.06, BL+RPU, no metadata compression
Codec ID                                 : dvhe
Codec ID/Info                            : High Efficiency Video Coding with Dolby Vision
Duration                                 : 28 min 44 s
Bit rate                                 : 24.4 Mb/s
Width                                    : 3 840 pixels
Height                                   : 1 920 pixels
Original height                          : 1 916 pixels
Display aspect ratio                     : 2.000
Original display aspect ratio            : 2.004
Frame rate mode                          : Constant
Frame rate                               : 23.976 (23976/1000) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.138
Stream size                              : 4.90 GiB (97%)
Default                                  : Yes
Alternate group                          : 1
Encoded date                             : 2021-09-08 03:08:22 UTC
Tagged date                              : 2021-09-08 03:08:41 UTC
Codec configuration box                  : hvcC+dvcC

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                                 : ec-3
Duration                                 : 28 min 44 s
Bit rate mode                            : Constant
Bit rate                                 : 768 kb/s
Maximum bit rate                         : 811 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                              : 158 MiB (3%)
Title                                    : English
Language                                 : English
Service kind                             : Complete Main
Encoded date                             : 2021-09-08 03:07:21 UTC
Tagged date                              : 2021-09-08 03:08:41 UTC
Complexity index                         : Not present / 16
Number of dynamic objects                : 15
Bed channel count                        : 1 channel
Bed channel configuration                : LFE
Dialog Normalization                     : -27 dB
compr                                    : -0.28 dB
dialnorm_Average                         : -27 dB
dialnorm_Minimum                         : -27 dB
dialnorm_Maximum                         : -27 dB

Text #1
ID                                       : 3
Format                                   : Timed Text
Codec ID                                 : tx3g
Duration                                 : 26 min 34 s
Bit rate mode                            : Variable
Bit rate                                 : 92 b/s
Frame rate                               : 0.537 FPS
Stream size                              : 17.8 KiB (0%)
Title                                    : English
Language                                 : English
Forced                                   : No
Encoded date                             : 2021-09-08 03:08:38 UTC
Tagged date                              : 2021-09-08 03:08:41 UTC
Count of events                          : 428

Dolby Vision profile seems relevant as, from the same source, I have absolutely no problem playing back Profile 8 or Profile 7 files. Same with HDR10 files. Everything P7, P8 or HDR10 works just fine, even for huge remuxes.

Last bit of very relevant information, I think, the same Misbehaving.mp4 file plays with no problem seeking back and forth when copied to local storage.

Are you connected via Wired ethernet or WiFi? I’ve seen something similar but it seemed to be related to the ethernet controller – even though it looked like a solid connection, switching to WiFi resolved the buffer. Its not the first ethernet-related issue I’ve seen with the AM6b+, but it has proven to be very difficult to diagnose.

Connected through gigabit ethernet. But this is happening only with these P5 DV files. I have 4K remuxes with far higher butrate that have no problem whatsoever.

Out of curiosity, does the problem repro on WiFi too?

It did not have much to do with Ethernet… it was more related to how I had rclone running on the box… Ended up changing the shares in order to access the remote shares from my home server and all appears to be good. There must me something in how DV files need data ahead that created the difference. If devs can understand from my logs, I remain available to go back to testing that scenario.
But from a personal point of view, I have solved the problem.

Thanks for chiming in.

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