WAV preset for 3CX / telephony systems
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Adds `wav-3cx` as a new FFmpeg output target that produces a WAV file
with the parameters required by 3CX and similar telephony platforms:
- Channel: mono (-ac 1)
- Sample rate: 8 kHz (-ar 8000)
- Bit depth: 16-bit PCM (-sample_fmt s16)
The target appears in the UI alongside the regular `wav` option under the
ffmpeg converter group. `normalizeOutputFiletype` maps `wav-3cx` → `wav`
so the downloaded file has the correct `.wav` extension.
URL query-param pre-selection
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Adds support for `?to=<format>&converter=<name>` query parameters on the
root page. When a user lands on the page with these params set, the
format selector is automatically pre-populated as soon as conversion
options finish loading (after the first file is selected).
Example:
http://localhost:3000/?to=wav-3cx&converter=ffmpegCloses#559
Signed-off-by: Radhakrishnan Pachyappan <gingeekrishna@gmail.com>
