Duration N/A wem

[papitis]

I got next error , my file was uploaded by BLOBS and joined them using CONCAT-FILES for some reason i can play this videos but it doesn't have a final time.

[opus @ 0x789a90] Warning: not compiled with thread support, using thread emulation
[vp8 @ 0x78a240] Warning: not compiled with thread support, using thread emulation
Input #0, matroska,webm, from '/data/in.webm':
Metadata:
encoder : Chrome
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0(eng): Audio: opus, 48000 Hz, mono, fltp (default)
Stream #0:1(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
At least one output file must be specified