mirror of https://github.com/mpv-player/mpv
f5d4f2aea4
Why a bigger search-interval is required: scaletempo2 doesn't do a good job when the signal contains frequencies less then 1/search_interval. With a search interval of 30ms that means anything below 33.333Hz sounds bad. Depending on the genre it's very for music to contain frequencies down to 30Hz, and sometimes even a little bit below that. Therefore a higher default value is needed to handle such cases. Based on that an argument can be made for a value of 50, as that should work down to 20Hz, or something even higher because movies sometimes have some infrasonic content. However the downside of big search intervals is increased CPU usage and intelligibility at higher speeds, as it effectively leads to parts of the audio being skipped. A value of 40 can handle frequencies down to 25Hz, enough for all music except very rare edge cases, while still providing decent intelligibility. Why a smaller window-size is required: Large values reduce intelligibility at high speeds and therefore small values are preferred. However when values get too small it starts to sound weird (similar to librubberband). In my testing a value of 10 already works well, but adding a small safety margin seems like a good idea, especially since it made no noticeable difference to intelligibility, which is why 12 was chosen. |
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| .. | ||
| af_drop.c | ||
| af_format.c | ||
| af_lavcac3enc.c | ||
| af_rubberband.c | ||
| af_scaletempo.c | ||
| af_scaletempo2.c | ||
| af_scaletempo2_internals.c | ||
| af_scaletempo2_internals.h | ||