ffmpeg ignores -seekable 0 when requesting hls key

[mmis1000]

Summary of the bug:
How to reproduce:

% ffmpeg -v debug -seekable 0 -icy 0 -f hls -i 'https://path-to-hls.host/manifest' test.mp4
ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers

...

[https @ 0x5b494dcf0700] request: GET /manifest HTTP/1.1
Accept: */*
Connection: close
Host: path-to-hls.host

...

[https @ 0x5b494dcfbf00] request: GET /key HTTP/1.1
Accept: */*
Range: bytes=0-
Connection: keep-alive
Host: path-to-hls.host

The manifest itself does obey -seekable 0 and not sent with range header. But the key file always send with range header no matter you set it as seekable or not and also there is no other way to disable range header.

[Jack Lau]

you could try with -http_seekable 0 and -seekable 0 to disable the range header of hls.

After reading the source code, I found that the seekable option memory is released after being used once. However, in this case, the HLS HTTP request is divided into two parts which belong to different function lifecycles. The http_seekable parameter is specifically used for the second part.

My explanation may not be entirely accurate, but at the very least, you can try using both parameters simultaneously to temporarily meet your needs.

I am working on improving this part of the code to maximize the effectiveness of the seekable option alone.