I wonder if someone could point me in the right direction. My Panasonic Lumix camera seems to create 4 audio tracks by default in its .MOV format. With my on-board stereo microphone, output is a mono left channel, a mono right channel and two null (present but with no audio) channels. When I load Lumix footage into ShotCut I am getting what appears to be one of the channels duplicated or a mono mixdown of both. The vertical L and R mixer bars are always identical. When I export to MP4 and look at the output in e.g. Resolve it’s the same duplicated signal. I can delete tracks 3 and 4 in Resolve and pan 1 and 2 left and right respectively, but had hoped the ShotCut might have been able to bypass that process.
I found a solution by using FFMPEG directly. Example:
FFMPEG -i InputFile.MOV -filter_complex “[0:a] join=inputs=2:channel_layout=stereo” -vn StereoAudio.wav
ffmpeg -an -i InputFile.MOV -c copy videoonly.mp4
ffmpeg -i videoonly.MP4 -i StereoAudio.wav -c:v copy -c:a aac -map 0:v -map 1:a outputfile.mp4
FFMPEG must be installed on your device, admittedly. .MP4 doesn’t support .WAV audio, but aac (lower case) is okay. Filenames may be substituted as necessary.
Thanks to Singularity Club and trac.ffmpeg.org
Did you know that the Shotcut package includes ffmpeg.exe and related executables such as ffprobe and ffplay
Dan and I were just talking the other day about how we should add more audio matrix and downmix filters.
Try changing the clip’s Properties > Audio > Track to All.
Thanks for answering, Brian. One of your Leaders suggested Properties → Audio → Track to All. I didn’t see Track option in Right-click Properties → [Audio] Tab. The panel says Channels 1 (mono) so it’s maybe only picking up the first channel. I am going through Open File → {Select a file} → drag down to editor (possibly missing a step here). When Audio is detached it’s still one channel. When pull in what’s put through the above three FFMPEG commands I get Channels 2 (stereo) and instantaneous differences in the level are clear.
I have had a go at FFMPEG because I did a LITTLE Unix for a while at work. I knew nothing about it except that if you got a command structure with the right arguments for a task then you could document that and subsequently drop in the appropriate entities. So that’s how I approach FFMPEG; it’s hugely powerful, but hard for those with no command-window experience. I had started with ShotCut and was getting on quite well, even making a small donation, but then got stuck with a persistent synchronisation problem with a 3-camera setup. The audio was fine within the Editor but on export it was 3 - 5 frames out. It was fixable but meant an iterative cycle of export → check the MP4 → adjust → export → check. In the end I despaired and moved across to DaVinci Resolve, sorry.
It is there. When the combined channel count exceeds the configured amount in Settings > Audio Channels, Shotcut chooses the first N channels by each track in order. So, this would be the perfect and fairly obvious choice:
You are quite right, thank you. I had tried at first all of the available Audio settings options, 1, 2, 4, 6 tracks and got either two identical signals or a single mono track. When choosing the 4 tracks quad option resulted in a single mono track on the mixer I assumed that ShotCut was missing something. My mistake in the [Audio] Tab was thinking that the [Track] dropdown was telling me that 1 track had been imported with four possible configurations rather than that there were four tracks. I didn’t even look down to the bottom of the list. It is not the first stupid error I have made and it won’t be the last.
The upside is that I have learned a tiny bit more about FFMPEG and can now manipulate the Lumix 4 mono track audio format (L R null null) into a single stereo track.
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Thank you for your consideration, Brian, but surely not that many camera types interpret an external stereo microphone as two mono channels and two null channels. ShotCut interpreted effortlessly the output from the other three camcorders and Smartphone I have used. What puzzled me at first was that, when I changed Settings → Audio Channels to 4, the mixer showed a single mono signal. But your colleague showed me what setting to change, after I actually looked at the Tracks dropdown properly on the second attempt. The combination of Settings → Audio channels to 2 and Select track → Right-click → Audio → Track → All produced a working stereo output on export. Setting Audio channels to 4 produced 4 null audio tracks. My only claim for mitigation is that, when you release the Tracks dropdown it immediately disappears – you have to click, hold and drag down to get to All. That’s just an excuse though. You know what Captain Mainwaring would have said.
True, but the number of cameras that do this is growing. Panasonic cameras have a DMW-XLR2 hot shoe adapter which allows two XLR microphones to be connected and recorded as tracks 3 and 4. If microphones are not connected, the camera records 4 tracks anyway, with tracks 3 and 4 being silent. This sounds odd, but what it allows for is consistent workflow scripts regardless of whether the adapter was attached or not. Newer Sony cameras support an XLR adapter too.
Yes, absolutely, Austin. But the Lumix software doesn’t recognise when the hot shoe connection isn’t activated; it creates two extra channels with no data. I don’t think that can be turned off, and I don’t think it is possible to reconfigure channels 1 and 2 as a stereo set. It’s interesting that Windows properties Details registers channels as 1 (Mono) on the Lumix .MOVs. The exported MP4s correctly show Channels 2 (Stereo).