View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0001223 | ardour | bugs | public | 2006-04-24 21:08 | 2008-11-20 23:48 |
| Reporter | emmef | Assigned To | paul | ||
| Priority | normal | Severity | major | Reproducibility | always |
| Status | closed | Resolution | fixed | ||
| Summary | 0001223: Audio card input latency over-compensated | ||||
| Description | When recording, input latency is over-compensated, which results in newly recorded tracks that are slightly too early. The "negative delay" is about as large as Jack's Frames per period (-p) option. Other recording tools, like Muse, do NOT compensate for input latency and the recorded tracks are too late in a predictable fashion (the input latency) When you cannot use extremely low latencies (which should not be necessary when you don't use many plugins but mainly focus about accoustic multitracking) the effects of both timeshifts (Ardour negative, Muse positive) are extremely irritating. I sent reproduction details and some hardware details in the additional information. Thanx beforehand! | ||||
| Additional Information | *** Reproduce *** - Connect the analogue line-in and line-out of you audio card (mind the mixer settings) - Start a jack server (settings follow later) - Start ardour - Play one track, while recording another (in this way, the playback of this track will be recorded) - Zoom in at the recorded track and compare it to the played track Both tracks look very much alike (depending on the quality of your soundcard :-), but the track that was recorded later, is shifted slightly BACKWARDS in time... The shifts I measured where: JACK setting -r48000 -p1024 -n2 - the input latency is 1024 frames, or 21.3 ms according to ardour - the negative delay is approximately 956 frames JACK setting -r48000 -p2048 -n2 - the input latency is 2048 frames, or 42.7 ms according to ardour - the negative delay is approximately 1986 frames Soundcard: M-AUDIO Audiophile 2496 Processor: AMD64 X2 3800+ Memory: 2 GB dual channel DDR, no swap Jack is running with realtime priority 70, with a vanilla kernel that has is preemtive and has the big kernel lock preempted. | ||||
| Tags | No tags attached. | ||||
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I forgot to mention that I used no plugins during the tests |
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what version of JACK are you using? Latency compensation does not work correctly with JACK < 0.100.0. It requires features that were added to JACK for 0.100.0 |
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I'm using Jack 0.99.0 I'm currently upgrading to 0.100.7 (Gentoo testing). I will perform measurements with that version and get back to you. |
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jackd 0.100.7 hw:0|hw:0|2048|2|48000|0|0|hwmon|hwmeter|-|32bit 42.7 ms. latency, according to ardour The recorded latency now is 62 samples, which yields 1.29 ms and is very acceptible for me. |
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see bugnotes. a newer version of JACK was required. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2006-04-24 21:08 | emmef | New Issue | |
| 2006-04-24 21:08 | emmef | => emmef@dds.nl | |
| 2006-04-24 21:08 | emmef | Name | => Michel |
| 2006-04-24 21:12 | emmef | Note Added: 0002494 | |
| 2006-05-09 00:27 | paul | Note Added: 0002500 | |
| 2006-05-10 17:46 | emmef | Note Added: 0002503 | |
| 2006-05-10 18:38 | emmef | Note Added: 0002504 | |
| 2006-06-06 13:49 | paul | Status | new => resolved |
| 2006-06-06 13:49 | paul | Resolution | open => fixed |
| 2006-06-06 13:49 | paul | Assigned To | => paul |
| 2006-06-06 13:49 | paul | Note Added: 0002509 | |
| 2008-11-20 23:48 | seablade | Status | resolved => closed |
