Intermittent playback error after cropping a freshly uploaded video

[looselyrigorous]

Acknowledgment

• I have read the warning above and understand that TrueNAS configuration issues posted without a prior TrueNAS forum post will be closed and I will be banned.

Is this related to TrueNAS?

No

TrueNAS forum post link

No response

Describe the bug

Cropping videos through Fireshare’s UI intermittently results in a playback error:

MEDIA_ELEMENT_ERROR: Format error

Screenshot attached. Refreshing the page allows the cropped video to play as expected.

The issue seems more likely to occur when cropping a freshly uploaded video, although I haven’t established a consistent trigger.

During failed attempts, the server logs show FFmpeg successfully creating the cropped MP4 and generating its poster, followed immediately by nginx reporting “No such file or directory” when serving the crop.

I observed failures with 10-bit AV1 videos at both 1080p and 1440p. An H.264 crop worked during the same session, but I haven’t established whether the issue depends on codec.

To Reproduce

1. Upload a video and open it in Fireshare.
2. Shortly after uploading, apply a crop through the UI.
3. Attempt to play the cropped video.
4. Occasionally, the player displays a format error and playback fails.
5. Refresh the page—the cropped video then plays as expected.

Expected behavior

The cropped video should play once processing completes without requiring a page refresh.

Screenshots

Fireshare version

Fireshare v1.8.4-lite

Browser

Brave

Additional context

Environment

• Fireshare v1.8.4-lite
• Kubernetes: one StatefulSet replica, one container
• ARM64
• FFmpeg 5.1.9 (Debian)
• Persistent LINSTOR block-storage PVC mounted at /processed
• Traefik reverse proxy
• ENABLE_TRANSCODING=false

Logs excerpt

First attempt: 1080p, 10-bit AV1 with Opus audio

[2026-09-29 11:31:24,125] DEBUG in util: $ ffmpeg -y -ss 11.28 -i /processed/video_links/3b36deb002104f709fa67f6270bc3db6.mp4 -c copy -movflags +faststart /processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4

[libdav1d @ 0xc2ac573e5e10] libdav1d 1.0.0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/processed/video_links/3b36deb002104f709fa67f6270bc3db6.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso6av01iso2mp41
    encoder         : Lavf63.1.100
  Duration: 00:00:54.44, start: 0.000000, bitrate: 15070 kb/s
  Stream #0:0[0x1](und): Video: av1 (Main) (av01 / 0x31307661), yuv420p10le(tv, bt709), 1920x1080, 14956 kb/s, 60 fps, 60 tbr, 1000k tbn (default)
  Stream #0:1[0x2](und): Audio: opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp, 119 kb/s (default)

[mp4 @ 0xc2ac574b7bd0] track 1: codec frame size is not set
Output #0, mp4, to '/processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4':
  Stream #0:0(und): Video: av1 (Main) (av01 / 0x31307661), yuv420p10le(tv, bt709), 1920x1080, q=2-31, 14956 kb/s, 60 fps, 60 tbr, 1000k tbn (default)
  Stream #0:1(und): Audio: opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp, 119 kb/s (default)

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mp4 @ 0xc2ac574b7bd0] Starting second pass: moving the moov atom to the beginning of the file
frame= 2662 fps=0.0 q=-1.0 Lsize=   82028kB time=00:00:43.14 bitrate=15576.6kbits/s speed= 347x
video:81316kB audio:645kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.081810%

2026-09-29 11:31:24,396 INFO    util.create_video_crop:401 | Created crop /processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4 (start=11.28, end=None)

[2026-09-29 11:31:24,415] DEBUG in util: $ ffmpeg -v quiet -y -ss 0 -i /processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4 -vframes 1 -vf scale=iw:ih:force_original_aspect_ratio=decrease /processed/derived/3b36deb002104f709fa67f6270bc3db6/poster.jpg
[2026-09-29 11:31:25,393] DEBUG in util: Generated poster /processed/derived/3b36deb002104f709fa67f6270bc3db6/poster.jpg in 0.9779472351074219s (success=True)

2026/09/29 11:31:26 [error] 43#43: *8621 open() "/processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4" failed (2: No such file or directory) while sending to client, client: 10.200.2.92, server: _, request: "GET /_content/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4 HTTP/1.1", host: "clips.shednet.dev", referrer: "https://clips.shednet.dev/home"

2026/09/29 11:31:33 [error] 46#46: *8625 open() "/processed/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4" failed (2: No such file or directory) while sending to client, client: 10.200.2.92, server: _, request: "GET /_content/derived/3b36deb002104f709fa67f6270bc3db6/3b36deb002104f709fa67f6270bc3db6-cropped.mp4 HTTP/1.1", host: "clips.shednet.dev", referrer: "https://clips.shednet.dev/home"

2026/09/29 11:32:04 [alert] 43#43: *8648 sendfile() reported that "/processed/derived/3b36deb002104f709fa67f6270bc3db6/poster.jpg" was truncated at 136103 while sending response to client, client: 10.200.2.92, server: _, request: "GET /_content/derived/3b36deb002104f709fa67f6270bc3db6/poster.jpg HTTP/1.1", host: "clips.shednet.dev"

Second attempt: 1440p, 10-bit AV1 with Opus audio

[2026-09-29 11:42:00,854] DEBUG in util: $ ffmpeg -y -ss 35.47 -i /processed/video_links/40995b8bcfcfa2425282067f789a7298.mp4 -c copy -movflags +faststart /processed/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4

[libdav1d @ 0xb980a9fade10] libdav1d 1.0.0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/processed/video_links/40995b8bcfcfa2425282067f789a7298.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso6av01iso2mp41
    encoder         : Lavf63.1.100
  Duration: 00:01:01.57, start: 0.000000, bitrate: 14126 kb/s
  Stream #0:0[0x1](und): Video: av1 (Main) (av01 / 0x31307661), yuv420p10le(tv, bt709), 2560x1440, 13992 kb/s, 60 fps, 60 tbr, 1000k tbn (default)
  Stream #0:1[0x2](und): Audio: opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp, 119 kb/s (default)

[mp4 @ 0xb980a9fb0980] track 1: codec frame size is not set
Output #0, mp4, to '/processed/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4':
  Stream #0:0(und): Video: av1 (Main) (av01 / 0x31307661), yuv420p10le(tv, bt709), 2560x1440, q=2-31, 13992 kb/s, 60 fps, 60 tbr, 1000k tbn (default)
  Stream #0:1(und): Audio: opus (Opus / 0x7375704F), 48000 Hz, stereo, fltp, 119 kb/s (default)

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mp4 @ 0xb980a9fb0980] Starting second pass: moving the moov atom to the beginning of the file
frame= 1654 fps=0.0 q=-1.0 Lsize=   50166kB time=00:00:26.08 bitrate=15757.5kbits/s speed= 381x
video:49710kB audio:414kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.083955%

[2026-09-29 11:42:01,070] INFO in util: Created crop /processed/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4 (start=35.47, end=None)

[2026-09-29 11:42:01,089] DEBUG in util: $ ffmpeg -v quiet -y -ss 0 -i /processed/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4 -vframes 1 -vf scale=iw:ih:force_original_aspect_ratio=decrease /processed/derived/40995b8bcfcfa2425282067f789a7298/poster.jpg
[2026-09-29 11:42:02,460] DEBUG in util: Generated poster /processed/derived/40995b8bcfcfa2425282067f789a7298/poster.jpg in 1.3708710670471191s (success=True)

2026/09/29 11:42:02 [error] 44#44: *8922 open() "/processed/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4" failed (2: No such file or directory) while sending to client, client: 10.200.2.92, server: _, request: "GET /_content/derived/40995b8bcfcfa2425282067f789a7298/40995b8bcfcfa2425282067f789a7298-cropped.mp4 HTTP/1.1", host: "clips.shednet.dev", referrer: "https://clips.shednet.dev/home"

Workaround tested

I changed this directive in the running container’s nginx configuration:

open_file_cache max=10000 inactive=60s;

to:

open_file_cache off;

Then ran nginx -t and nginx -s reload. Cropping and playback appear to work afterward.

Possible explanation

The bundled configuration also contains:

open_file_cache_valid 120s;
open_file_cache_errors on;

The video route checks for a cropped file using try_files before falling back to the original. Could nginx cache a missing-file lookup before the crop is created and continue using it afterward?

I haven’t confirmed nginx’s cache state during the failures or checked the file directly while nginx was reporting it missing. I also don’t know why the H.264 attempt worked while the AV1 attempts failed.

[ShaneIsrael]

Will look into this.