Hello all,
We are experiencing a persistent issue with LTC timecode updates (backward time jump) on our system. When we set a new timecode (for example, by jumping the hour), the connected LTC reader does not update immediately. Instead, it only updates after approximately 2 minutes, and then starts updating subsequent frames as expected.
Issue pattern:
• Time is set (during init)
• Wait for ~2 minutes (time not updated on LTC reader)
• After 2 minutes, the time updates, but only from the 2nd frame onward
What we have tried:
• Modified the code to “freeze” the timecode at each new value for 30 seconds
• Inserted a short period of silence (LTC break) before each timecode jump
• Output a burst (e.g., 2 seconds) of incrementing LTC at the new timecode, then freeze or repeat as needed
• Set the LTC timecode to the current system clock time for each frame
• Utilized snd_pcm_reset and snd_pcm_avail_update PCM functions
• Updated the time continuously (e.g., 25 times in 1 second, 50 times in 2 seconds, 75 times in 3 seconds)
• Modified the code to reinitialize both the LTC encoder and the ALSA library
• None of the above attempts have resolved the “backward time jump” issue
Observed logs:
(Same behavior occurs when trying to update the time every 30 seconds)
text
sample rate: 48000.00
frames/sec: 25.00
sample format: 8bit unsigned mono
Playing LTC via ALSA. Timecode hour will jump every 30 seconds. Press Ctrl+C to stop.
Timecode updated to 03:40:59:00 ==> Time not updated
Timecode updated to 04:40:59:00 ==> Time not updated
Timecode updated to 05:40:59:00 ==> Time not updated
Timecode updated to 06:40:59:00 ==> Time updated to 03:40:59:00
Timecode updated to 07:40:59:00 ==> Time updated to 04:40:59:00
Request:
Has anyone encountered similar behavior with LTC timecode device (Deity TC-1) or ALSA-based LTC playback?
Is there a known workaround or best practice for forcing an immediate timecode update (especially for backward jumps) that works reliably with hardware LTC timecode device (Deity TC-1)?
Any insights or suggestions would be greatly appreciated!
Thank you.
Hello all,
We are experiencing a persistent issue with LTC timecode updates (backward time jump) on our system. When we set a new timecode (for example, by jumping the hour), the connected LTC reader does not update immediately. Instead, it only updates after approximately 2 minutes, and then starts updating subsequent frames as expected.
Issue pattern:
• Time is set (during init)
• Wait for ~2 minutes (time not updated on LTC reader)
• After 2 minutes, the time updates, but only from the 2nd frame onward
What we have tried:
• Modified the code to “freeze” the timecode at each new value for 30 seconds
• Inserted a short period of silence (LTC break) before each timecode jump
• Output a burst (e.g., 2 seconds) of incrementing LTC at the new timecode, then freeze or repeat as needed
• Set the LTC timecode to the current system clock time for each frame
• Utilized snd_pcm_reset and snd_pcm_avail_update PCM functions
• Updated the time continuously (e.g., 25 times in 1 second, 50 times in 2 seconds, 75 times in 3 seconds)
• Modified the code to reinitialize both the LTC encoder and the ALSA library
• None of the above attempts have resolved the “backward time jump” issue
Observed logs:
(Same behavior occurs when trying to update the time every 30 seconds)
text
sample rate: 48000.00
frames/sec: 25.00
sample format: 8bit unsigned mono
Playing LTC via ALSA. Timecode hour will jump every 30 seconds. Press Ctrl+C to stop.
Timecode updated to 03:40:59:00 ==> Time not updated
Timecode updated to 04:40:59:00 ==> Time not updated
Timecode updated to 05:40:59:00 ==> Time not updated
Timecode updated to 06:40:59:00 ==> Time updated to 03:40:59:00
Timecode updated to 07:40:59:00 ==> Time updated to 04:40:59:00
Request:
Has anyone encountered similar behavior with LTC timecode device (Deity TC-1) or ALSA-based LTC playback?
Is there a known workaround or best practice for forcing an immediate timecode update (especially for backward jumps) that works reliably with hardware LTC timecode device (Deity TC-1)?
Any insights or suggestions would be greatly appreciated!
Thank you.