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Revert int16 pack encoding (caused static), keep float-to-s16 drain 

Setting (mixed:encoding pack) :int16 after server creation did not
change the pack's internal buffer format — data was still written as
float but read as int16, producing garbage audio.

Added TODO comment to investigate correct API for setting pack encoding
at creation time. The float→s16 conversion in Lisp works correctly.
This commit is contained in:
Glenn Thompson 2026-03-06 11:30:53 +03:00
parent f594daabf8
commit df9d939a2f
1 changed files with 9 additions and 5 deletions
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14
cl-streamer/harmony-backend.lisp
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@ -55,6 +55,12 @@
(defmethod mixed:start ((drain streaming-drain))) (defmethod mixed:start ((drain streaming-drain)))
(declaim (inline float-to-s16))
(defun float-to-s16 (sample)
"Convert a float sample (-1.0 to 1.0) to signed 16-bit integer."
(let ((clamped (max -1.0 (min 1.0 sample))))
(the (signed-byte 16) (round (* clamped 32767.0)))))
(defmethod mixed:mix ((drain streaming-drain)) (defmethod mixed:mix ((drain streaming-drain))
"Read interleaved float PCM from the pack buffer, encode to all outputs. "Read interleaved float PCM from the pack buffer, encode to all outputs.
The pack buffer is (unsigned-byte 8) with IEEE 754 single-floats (4 bytes each). The pack buffer is (unsigned-byte 8) with IEEE 754 single-floats (4 bytes each).
@ -171,6 +177,9 @@
(old-drain (harmony:segment :drain output)) (old-drain (harmony:segment :drain output))
(pack (mixed:pack old-drain)) (pack (mixed:pack old-drain))
(drain (pipeline-drain pipeline))) (drain (pipeline-drain pipeline)))
;; TODO: Investigate setting (mixed:encoding pack) :int16 to let cl-mixed
;; handle float→s16 in C. Currently causes static — may need to be set
;; before server start, or pack may need recreation with correct encoding.
;; Wire our streaming drain to the same pack buffer ;; Wire our streaming drain to the same pack buffer
(setf (mixed:pack drain) pack) (setf (mixed:pack drain) pack)
;; Swap: withdraw old dummy drain, add our streaming drain ;; Swap: withdraw old dummy drain, add our streaming drain
@ -505,8 +514,3 @@
(log:error "play-list thread crashed: ~A" e)))) (log:error "play-list thread crashed: ~A" e))))
:name "cl-streamer-playlist")) :name "cl-streamer-playlist"))
(declaim (inline float-to-s16))
(defun float-to-s16 (sample)
"Convert a float sample (-1.0 to 1.0) to signed 16-bit integer."
(let ((clamped (max -1.0 (min 1.0 sample))))
(the (signed-byte 16) (round (* clamped 32767.0)))))