The AY volume-bar indicator (music_analizator) ran inside int_text_off,
the same precisely-timed interrupt chain that switches between text and
graphics video modes. Its DMA clear + page switching + drawing could
overrun that timing budget on dynamic tracks, causing visible vertical
stripe flicker. Moved it to the main loop (once per frame, after
wait_frame) instead, leaving the player tick (pt_play) and its tempo
timing untouched inside the interrupt.
Also waits for the DMA clear to finish before drawing bars into the
same memory (previously a write race).
alex