2025-11-01 10:48:10.652 T:1208 info <general>: ffmpeg[0x212e50a0]: [https] Opening 'https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-audio-aac-sv-tts-2ch-130/cmaf-audio-aac-sv-tts-2ch-130-init.mp4' for reading
2025-11-01 10:48:10.653 T:1208 info <general>: ffmpeg[0x212e50a0]: [hls] Opening 'https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-audio-aac-sv-tts-2ch-130/cmaf-audio-aac-sv-tts-2ch-130-107195.mp4' for reading
...
2025-11-01 10:48:10.770 T:1208 info <general>: ffmpeg[0x212e50a0]: [hls] No longer receiving playlist 3 ('https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-video-avc-448x252p50-1100/cmaf-video-avc-448x252p50-1100.m3u8')
...
2025-11-01 10:48:10.778 T:1208 info <general>: ffmpeg[0x212e50a0]: [https] Opening 'https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-video-avc-1920x1080p50-6000/cmaf-video-avc-1920x1080p50-6000-107196.mp4' for reading
...
2025-11-01 10:48:10.908 T:1044 debug <general>: ActiveAE::SyncStream - average error of -35.808218, start adjusting
2025-11-01 10:48:10.908 T:1044 debug <general>: ActiveAE::SyncStream - average error -0.016552 below threshold of 30.000000
...
2025-11-01 10:48:13.342 T:1214 debug <general>: CPtsTracker: detected pattern of length 1: 19999.99, frameduration: 20000.000000
2025-11-01 10:48:13.771 T:1215 info <general>: CVideoPlayerAudio::Process - stream stalled
2025-11-01 10:48:14.174 T:1214 debug <general>: CDVDVideoCodecDRMPRIME::GetPicture - flush buffers
...
2025-11-01 10:48:14.480 T:1208 info <general>: ffmpeg[0x212e50a0]: [https] Opening 'https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-video-avc-1920x1080p50-6000/cmaf-video-avc-1920x1080p50-6000-init.mp4' for reading
2025-11-01 10:48:14.483 T:1208 info <general>: ffmpeg[0x212e50a0]: [hls] Opening 'https://ed0-as2119.cdn.svt.se/l1/se/svt1/19a2a5efb80/cmaf-video-avc-1920x1080p50-6000/cmaf-video-avc-1920x1080p50-6000-107197.mp4' for reading
2025-11-01 10:48:14.784 T:1214 debug <general>: CPtsTracker: pattern lost on diff 3200000.000000, number of losses 1
2025-11-01 10:48:15.308 T:1214 warning <general>: OutputPicture - timeout waiting for buffer
...
2025-11-01 10:48:15.842 T:1214 warning <general>: OutputPicture - timeout waiting for buffer
...
2025-11-01 10:48:16.375 T:1214 warning <general>: OutputPicture - timeout waiting for buffer
2025-11-01 10:48:17.719 T:1042 info <general>: Skipped 1 duplicate messages..
2025-11-01 10:48:17.719 T:1042 debug <general>: CLibInputKeyboard::ProcessKey - using delay: 500ms repeat: 33ms
2025-11-01 10:48:17.719 T:1224 debug <general>: Thread Timer start, auto delete: false
2025-11-01 10:48:17.743 T:1037 debug <general>: Keyboard: scancode: 0x2d, sym: 0x78 (x), unicode: 0x78, modifier: 0x0
2025-11-01 10:48:17.743 T:1037 debug <general>: HandleKey: x (0xf058) pressed, window 12005, action is Stop
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I'm not an expert in reading streaming service logs (and different services will behave differently) but it looks like audio and video are separate streams, and everything goes through a normal looking process of obtaining stream manifestsa and then selecting audio and video streams. The audio stream looks to be selected, but then the video stream switches from SD (448x252@50) to HD (1080p@50) and then the stream stalls.
There are quite a lot of streaming add-ons installed so I would be interested to see logs from a current LE13 nightly that has only the SVT play and inputstream.adaptive add-ons installed. I'm not expecting anything to be different, but it will remove some noise from the log. I don't see any 'errors' that would e.g. indicate Python issues or something that traces back to the underlying OS. IMHO if there's a difference between the add-on under LE and the add-on the author tested on Ubuntu it's more likely to be add-on or i.a configuration and not the OS environment.
NB: The stream is H264 and RPi5 does not have H264 hardware decode or hardware deinterlacing so the v4l2_m2m errors in the log that Da Flex has seized upon are nothing more than ffmpeg correctly failing to find hardware decode and deinterlace /dev/video nodes that don't exist and failing back to use software capabilities. All normal and expected on an RPi5 device.