Subject: Re: [linux-audio-dev] hdr disk throughput
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Tue Mar 14 2000 - 10:05:03 EST
Paul you are missing the point IMHO,
As far I can understand you have
N channels playing, and you want instantly
switch some of these channels (up to N if you want)
in the record mode.
That means if you don't have 24 channels playing
AND recording all the time.
And since you don't need sustained double
performance, but only when switching some channels from/to
recordmode/playmode, your problem is easily solved by buffering.
With buffers large enough, the application will easily be able
to buffer new recording channels into mem, and as soon the
track is out of the playback mode, the disk thread can begin the write
to the disk. (or you could even overlap the times, since the buffer
will overcome to the momentarily performance lack of the disk).
PS: what kind of enhancements do you plan for ardour's buffering scheme ?
(you talked about it in your other mail)
I can't recall your initial punch-in/out problems ? application stalls ?
Can you explain us again what is still needed to make adrour
satisfy all your pro-studio needs ?
:-)
BTW, how long does take a random seek in ardour at 24 tracks:
ie: when you seek from the begging to the middle, how many
secs (or fractions) pass until you can hear the audio again ?
just curious :-)
Benno.
On Mon, 13 Mar 2000, Paul Barton-Davis wrote:
> i am a little worried.
>
> it seems to me that in order to offer "true professional level" HDR,
> one has to sustain twice the apparent rate of disk i/o.
>
> the feature that causes this is the ability to move instantly in and
> out of record mode. when transitioning from record to play, people
> expect no break in the audio stream. that means that you must have the
> playback data (from the disk) already read into a memory buffer ready
> for use. but since you have no idea when this transition may occur,
> you actually have to do this *all the time* you are recording - punch
> out could happen anywhere.
>
> thus, in a record-all-tracks situation, to offer this feature, you
> have to be able to stream the given data rate both to *and* from the
> disk.
>
> comments ?
>
> --p
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