rtsp method PLAY fails (status_code = 400) with some locales (non-English like)

[Ivan]

In libavformat/rtspdec.c:
...
rtsp_read_play()
{
...

snprintf(cmd, sizeof(cmd),

"Range: npt=%0.3f-\r\n",
(double)rt->seek_timestamp / AV_TIME_BASE);

...
}
"cmd" can contain "Range: npt=0,000-" instead of "Range: npt=0.000-"
bacause of some applications use a locale with a comma as a decimal delimiter.
This case RTSP request will return a status code 400 (Bad Request).
xxprintf functions use current locale settings, see <locale.h>

History:
I tried to play a RTSP stream in a Qt library based application.
Result: av_open_input_file fails, but a non-Qt applications and tutorials play streaming video. Tracing a source of error I found that "Range: npt=0,000-" sent with a PLAY method. Qt changes ansi C locale to a current system locale. Default decimal delimiter is a comma in my case. It was a reason of my troubles. Now I call setlocale(LC_ALL, "C") before open a stream to make some fast crutch.

[Carl Eugen Hoyos]

Could you test attached modification?

[Ivan]

This modification works. Thanks you.

[Carl Eugen Hoyos]

Fixed in latest git.
Thank you for the very helpful report!