Read out Stream IDs with ffprobe

[nel-son]

Hi,

i'm writing a little shell script to demux all streams i want from a matroska file, rename it with the most important information in the file name and convert the audio streams if i want it. When i read the streams numbers of all audio streams with

ffprobe -v error -select_streams a -show_entries stream=index -of csv=p=0 file.mkv

the output is

1
2

But if i want to read information about a specific stream the numbers starting with 0.

ffprobe -select_streams a:1 -show_entries stream=bit_rate -v quiet -of default=noprint_wrappers=1 file.mkv

Gives me the information of stream 2 not 1 and "a:2" is empty.

Is this correct? Is there something wrong with my command?