Ram usage when using ardour

(Mrskytown11) #1

When ardour is running does the audio tracks get copied into ram or does it stream from my drive, so let’s ssy a session has 500mb of audio files would the system memory manager show a number above 500mb, I assume plugins use up ram as well.

(Anahata) #2

It streams from your drive. The length of the session makes little or no difference to RAM usage.

(Mrskytown11) #3

What are the typical streaming rates 24 bit 48k streams

(Seablade) #4

Um… yes?

It reads the files off the hard drive into a buffer (The size of which is set in preferences) and plays it out from there. Not real sure what your question is?


(Mrskytown11) #5

Oh ok so it doesn’t constantly stream from the drive, it buffers the files then playback?

(Chris) #6

The buffer size is set by time, so for example you set the buffer to 5 seconds, once it has played half a second of audio there is no longer 5 seconds of data in the buffer, so it reads in more data. It is constantly streaming from the drive to fill the buffer up again once part of the data in the buffer has been played. The average streaming rate will be the same as the bit rate per track times the number of tracks. Because of the way disk interfaces work it will end up being higher data movement part of the time, lower part of the time, but the average always has to work out to the same data rate as the audio you are playing.

(Mrskytown11) #7

Oh ok thanks for the information

(Robin Gareus) #8

Just multiply the two numbers. For each channel of audio:

24 bit/sample * 48000 samples/second = 1152000 bits/sec = 140kbytes/sec

As others have already pointed out, this is the average. Ardour/Linux reads a couple of MBytes in a few msec from disk to a RAM buffer and then the disk idles for a couple of seconds.

A boring cheap consumer-grade USB2 disk can write 40MB/sec, using Ardour’s default (32bit float) you can, at best, record 40 * 1024 * 1024 [byes/sec] / (4 [bytes/sample] * 48000 [samples/sec / channel]) = 218 channels simultaneously.

Internal disks are a lot faster 200-400MB/sec are common and SSDs easily get into he GB/sec range on average.

Back on subject. the 5 sec disk-cache per track is small. that’s only a MB (per channel). When adding a track, a lot more memory consuming objects are created.

(Mrskytown11) #9

Ahh Ic Ic cool thanks.

(Mrskytown11) #10

From this website it gives me a higher kbps for 24 bit 48Khz audio, which one is correct


(Chris) #11

Higher than what? I went to that website, selected 48k sample rate, 24 bits per sample, one channel, and it gave Bit Rate: 1152 kbps, i.e. 1152000 bits per second,
Robin previously wrote:

Same value. Not quite sure what you are confused about.