Never heard of PCA, perhaps you meant PCM?
Regardless, should retain the Audio at highest quality possible - yours sounds like it may be 48,000Hz, 16 Bit - therefore retain as either the format as is, or render as "Wave(Microsoft) (*.wav)" and selecting the "Audio: 48,000 Hz, 24 Bit, Stereo, PCM" template
Whoever whenever needs some thunder sound can drop me an e-mail:) In the end we are all the members of big big big family:)
Tonight I feel that I'm in the mood of learning something about audio formats.
(As being someone who has heavy hearing loss and uses hearing aid, all these infos about audio, sounds to me like science fiction)
So I checked the videos that I took with Sony HDD camera :
Dolby AC-3, 48.000 Hz, 5.1 Surround (stereo downmix)
Which one is better? Should I use next time Sony camera for such situations?
For recording thunder etc.
I remember that, when I used to open videos coming from Sony HDD camera in Vegas timeline, I used to see four lines of audio but not anymore!
Dolby AC-3 is a lossy compression format, which means that some of the quality is lost every time audio is saved in that format. It's not much loss, but it is there. The trade off is that typical AC-3 files are only about 1/11 the size of uncompressed WAV, which is why it's used for the limited space of DVDs and other disc formats.
"I remember that, when I used to open videos coming from Sony HDD camera in Vegas timeline, I used to see four lines of audio but not anymore!"
If the camera records 5.1 surround sound you will see it on the Vegas Pro timeline if you set the Project Audio Properties to 5.1 before putting you media on the timeline. I have not found it to work by changing the Audio properties after the fact.
There's no advantage in rendering the audio on the timeline into AC-3 for "safe keeping". That will be recompressing lossy format into lossy format, creating more loss. Saving this for later use just means another lossy recompression added into the chain. If you've saved the uncompressed WAV you can always create any compressed version from this later when you need it, without adding in the third recompression.
Now, if you use a tool that de-muxes and pulls the audio track directly out of the file and saves it, this is fine. Vegas is not one of those tools.
PCA is a SCS loss-less format. Which is fine for SCS software, if the PCA file(s) need to go to a third-party who uses non-SCS Apps, the files would need to opened and saved .. in a cross platform/application file type.. normally WAVE or AIFF.