diff options
Diffstat (limited to 'modules')
| -rw-r--r-- | modules/video-audio-recording-capture.el | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/modules/video-audio-recording-capture.el b/modules/video-audio-recording-capture.el index 069975bc..ea0d687c 100644 --- a/modules/video-audio-recording-capture.el +++ b/modules/video-audio-recording-capture.el @@ -229,7 +229,12 @@ On X11: ffmpeg captures screen directly via x11grab with PulseAudio audio." (defun cj/recording--build-audio-command (mic-device system-device filename) "Build the ffmpeg shell command string for audio-only recording. MIC-DEVICE and SYSTEM-DEVICE are PulseAudio device names. FILENAME is -the output .m4a path. Mixes mic + system monitor into a single AAC file." +the output .flac path. Mixes mic + system monitor into a single lossless +FLAC file. FLAC is used instead of AAC/M4A for two reasons: it is +lossless (no encoder-quality loss, which matters for transcription +accuracy), and its frames are self-contained so an abruptly stopped +recording is still decodable -- unlike MP4, which needs a moov trailer +written at close." (format (concat "ffmpeg " "-f pulse -i %s " ; Input 0: microphone "-f pulse -i %s " ; Input 1: system audio monitor @@ -238,8 +243,7 @@ the output .m4a path. Mixes mic + system monitor into a single AAC file." "[1:a]volume=%.1f[sys];" "[mic][sys]amix=inputs=2:duration=longest[out]\" " "-map \"[out]\" " - "-c:a aac " - "-b:a 64k " + "-c:a flac " "%s") (shell-quote-argument mic-device) (shell-quote-argument system-device) @@ -287,10 +291,10 @@ Uses wf-recorder on Wayland, x11grab on X11." (defun cj/ffmpeg-record-audio (directory) "Start an audio recording, saving output to DIRECTORY. Records from microphone and system audio monitor (configured device), -mixing them together into a single M4A/AAC file. +mixing them together into a single lossless FLAC file. The filter graph mixes two PulseAudio inputs: - [mic] → volume boost → amerge → AAC encoder → .m4a + [mic] → volume boost → amix → FLAC encoder → .flac [sys] → volume boost ↗" (cj/recording-check-ffmpeg) (unless cj/audio-recording-ffmpeg-process @@ -299,7 +303,7 @@ The filter graph mixes two PulseAudio inputs: (system-device (cdr devices)) (location (expand-file-name directory)) (name (format-time-string "%Y-%m-%d-%H-%M-%S")) - (filename (expand-file-name (concat name ".m4a") location)) + (filename (expand-file-name (concat name ".flac") location)) (ffmpeg-command (cj/recording--build-audio-command mic-device system-device filename))) (message "Recording from mic: %s + ALL system outputs" mic-device) @@ -370,7 +374,7 @@ for ffmpeg to write container metadata before giving up." (defun cj/audio-recording-stop () "Stop the audio recording, waiting for ffmpeg to finalize the file. Sends SIGINT to the process group and waits up to 3 seconds for ffmpeg -to flush audio frames and write the M4A container trailer." +to flush audio frames and finalize the FLAC stream." (interactive) (if (not cj/audio-recording-ffmpeg-process) (message "No audio recording in progress.") @@ -379,8 +383,10 @@ to flush audio frames and write the M4A container trailer." (let ((pid (process-id proc))) (when pid (signal-process (- pid) 2))) - ;; M4A finalization is faster than MKV, but still needs time to write - ;; the AAC trailer and flush the output buffer. + ;; On a clean stop ffmpeg seeks back and backfills the FLAC STREAMINFO + ;; (total samples, MD5) so duration reads correctly. Even a hard + ;; truncation leaves a decodable file, since FLAC frames are + ;; self-contained -- there is no end-of-file trailer to miss. (let ((exited (cj/recording--wait-for-exit proc 3))) (unless exited (message "Warning: recording process did not exit within 3 seconds"))) |