Loading audio files

LTCast reads the whole song into memory when it loads it, so playback never waits on the disk. If the audio file contains an embedded LTC track, LTCast reads the timecode directly from that signal while the song plays; if not, it generates timecode from the playhead position.

Ways to load a file

• Drag and drop — drag one or more audio files from your file manager onto the LTCast window; drop them anywhere on it. They are added to the setlist and the first one is loaded
• File menu — File → Load Song (Audio)… opens a file picker and loads one file into the player without adding it to the setlist
• Drop zone — while nothing is loaded, the centre panel shows Drop audio file here or click to open; clicking it opens the same file picker
• From the setlist — click the ▶ on a song card; see Song card overview

Supported formats: .wav, .aiff / .aif, .mp3, .flac, .ogg, .m4a.

What happens after loading

Once a file is loaded, LTCast:

• Draws the music waveform in the waveform view
• Scores every channel of the file for an embedded LTC signal (a mono file is never treated as LTC)
• Draws the thin LTC strip at the bottom of the waveform view
• If the LTC does not start at the beginning of the file, shows an LTC starts at … banner under the timecode

The large timecode display shows dashes until playback starts. Once the song plays, it shows the timecode read from the file, and the detected frame rate appears in the Force FPS row under the digits.

If no LTC is found in the file, LTCast switches to the TC Generator and counts timecode from the song's Start TC, which is 00:00:00:00 unless you set one. In Generator mode a Start TC field (stored per song) and a frame-rate selector appear under the digits — that is where you choose the start address. The Global Offset shifts timecode by a fixed number of frames; it is not the control for picking a start address.

LTC channel auto-detection

LTCast scores each channel of the file in short windows — at the start, every 30 seconds, and at the end — and selects the channel that looks most like LTC. The result is shown in Settings → Devices as LTC detected on CH n (or LTC not detected). The LTC Track selector next to it lets you override the choice:

• Auto-detect — LTCast picks the best channel automatically (default)
• CH 1 to CH 4 — force LTC decode from that channel

Override the channel manually if the auto-detection picks the wrong one, or if your file has LTC on a specific channel by convention.

Frame rate auto-detection

While the song plays, LTCast reads the embedded LTC signal and identifies the frame rate: 24, 25, 29.97 Drop-Frame, or 30 fps. The detected rate appears in the Force FPS row under the timecode display.

If the auto-detection picks an incorrect rate — for example, if the file has a low signal level that makes detection ambiguous — use the Force FPS buttons (Auto, 24, 25, 29.97, 30) to override it. LTCast will decode the LTC using the forced rate regardless of what it detects from the signal.

File size and long songs

LTCast does not stream songs from disk: it reads and decodes the whole file into memory. Ordinary songs load in moments. Network locations work as long as they are mapped to a drive letter (for example Z:\) or, on a Mac, mounted under /Volumes; paths that start with \\server\share or //server/share are refused. Local storage is still recommended for shows.

Songs up to about 3 hours

A single song can be up to about 3 hours 6 minutes long (at a 48 kHz output device; about 3 hours 22 minutes at 44.1 kHz). Long songs, files over 500 MB, and AIFF files (at any length) are decoded by ffmpeg into a temporary file first and then copied into memory, so they take a while to load:

• The line under the big timecode shows Loading N% with a thin progress bar, then Preparing… while LTCast scans the song for LTC. The window can pause for a few seconds during Preparing…
• You can press Play while a song is still loading; it starts as soon as the song is in
• Memory — a 3-hour stereo song takes about 4 GB in memory, and for a few seconds during a song change the old and the new song are both held. LTCast uses at most half of the computer's RAM (and never more than 12 GB) for one song. We recommend 16 GB of RAM if you play 3-hour songs
• Disk space — LTCast needs free space in the system's temporary folder for the decoded file (the size of the decoded song plus about 1 GB spare); it is deleted afterwards
• Looping a whole song (the loop button next to A and B) wraps cleanly at the end of a long song too

If a song cannot be loaded, LTCast says why:

• Not enough memory to load this song — close other programs and try again
• Not enough disk space to load this song: it needs about N GB of temporary space — free up space and try again
• This file has no sound in it, so it cannot be loaded — the file has no audio track
• Reading this file took too long to answer — an external drive may still be starting up; try again
• This audio could not be decoded — the file may be damaged or in a format that is not supported
• This audio file is too long to load — it is over the limit above; split it and load the parts

Video files

Video files (.mp4, .mov, etc.) are not loaded through the audio file path. With a song loaded, use File → Import Video (or the import button in the Video Audio row under the waveform) to attach a video reference file. See Importing a video for details.