When sending an AV1-encoded video, Telegram Android does not transcode or downscale it. The original file is uploaded unmodified, with no compression option and no error shown. Recipients without AV1 support get audio but no video, previews break, and a 4K clip uploads at full size (~126 MB) instead of 1080p. Any other codec is handled correctly - this is specific to AV1.
STEPS: 1. Put a 4K AV1 .mp4 on the device (e.g. Pixel "Video Boost" output). 2. Send it in any chat, via gallery picker or system share sheet. 3. It uploads at original size and resolution. 4. Repeat with an identical 4K HEVC/H.264 file - correctly transcoded to 1080p H.264.
EXPECTED: AV1 transcoded like any other non-AVC source, or rejected with a clear message. ACTUAL: the original is uploaded untouched, silently.
4K AV1 of identical resolution, duration and HDR - neither line appears, no video encoder is created, and upload starts straight from the original path: "debug_uploading: send reqId 9449 /storage/emulated/0/Download/TEST_4K_AV1_reencoded.mp4 file_part=0 isBig=true". Only c2.google.av1.decoder is instantiated, in mediaserver, for thumbnails.
Both entry routes and both resolutions were tested, so route and resolution are excluded - only the codec matters. The AV1 file was freshly re-encoded, so its hash and decoded content differ from anything sent before, ruling out deduplication. Pixel "Video Boost" returns AV1 and Pixel 10 exposes AV1 recording, so this is increasingly common.
Steps to reproduce
Put a 4K AV1-encoded .mp4 on the device (e.g. a Pixel "Video Boost" clip, which is returned as AV1).
Open any chat, tap the paperclip icon, select the AV1 video from the gallery, and tap send.
The video uploads at its original size and resolution. No compression option is offered, it is not downscaled to 1080p, and no error is shown.
Repeat step 2 with a 4K HEVC or H.264 file of identical resolution and duration.
That file is correctly transcoded and downscaled to 1080p H.264, confirming the difference is the codec and not the resolution.
The same difference occurs if the videos are shared into Telegram via the system share sheet instead of the in-app picker.
Device info
Telegram Android 12.9.1 (69792), Google Pixel 9 Pro, 17 (37)