- Posts: 4
- Joined: Mon Apr 03, 2017 1:03 am
Mon Apr 03, 2017 5:16 am
Greetings to all users and fellow Blackmagic aficionados!
This is my first post on the forum, as I've been an avid watcher/checker here and the tips and advice from you all have been an amazing help and value to my usage of BM products. I wanted to post my first tip to everyone out there who has a Blackmagic Pocket Cinema Camera, and *may* want to use the internal mics for whatever reason.
Also, if this all seems TL/DR, or obvious, I apologize. I only intended to inform and inspire. Cheers!
Perhaps someone on here has already posted about the internal mics and outboard fixes that make the BMPCC a great usable solution for audio. As an audio engineer myself, I wanted to dig in deeper into the BMPCC's recording system and shed some light on my findings.
So I've seen many posts here (and everywhere else online) where users speak about the BMPCC's internal mics, and how they are very bad for recording anything usable. That got me to thinking... Why is that?
I started by recording a RAW video, all settings set to maximum quality, and audio settings to their defaults, using the Internal microphones, so that I could grab the unaltered WAV file for analyzing. After transferring to the computer, what I heard was just... YUCK!
I loaded up my favorite DAW, and opened a spectrum analyzer. These were my findings:
RAW Audio coming from the BMPCC is recorded at 48,000KHz, 2 Channel (Stereo), encapsulated as an uncompressed 'WAV' file. Pretty impressive sampling rate, two channels of audio, and should be able to include enough data for the high-end frequency spectrum, right? Well...
It seems that Blackmagic have placed a Lo-pass filter on their final output stage, set to about 4.00KHz, rolling off ALL of the audio data from 4KHz and above, with about a -40db reduction in volume.
I intended to check if this frequency range of audio was restorable in post. I loaded a few instances of 8-band Equalizers, and started applying a boost roll-off of frequency ranges from 4KHz, all the way to 20,000KHz, to keep things linear and smooth. The problem was, one instance of an EQ was not enough to bring up the gain in that range to the audible level yet. So I added another EQ with duplicated settings to the chain.
After some further tweaking... Success! The highs were THERE and equalized! The data is actually in the file, all being recorded perfectly! So why was it that Blackmagic placed this filter there? I kept listening... and I found out why.
There seems to be a bit of high-frequency interference at a few bands of the spectrum up there, always at the same spots in the analyzer. This is due to the very complex circuitry involved in the capturing of video through the lens, the sensors, and various other chips and ICs that create these high-pitched noises. No problem, I applied about 3 notch filters onto my EQ's, honed in on the exact frequency that the noises were being emitted from, and applied a precise cut to them.
The resulting audio when A/B'ed against original file was just amazing. Crisp highs, great mids that were already there, and I'd say a decent low frequency range being captured as well. All from the built-in microphones! Now, I know... this may be extra work that people would need to do just to get a better recording out of some built in microphones when there are surely better outboard alternatives out there. But I figured I'd give it a shot, and it worked.
I have uploaded a test recording of the audio unaltered, and the audio processed using my above-mentioned EQ chain. WAVs needed to be converted to MP3s to save space on the upload. Since recording from the microphone, the only setting that applies is 'Microphone Input' on the BMPCC. I had mine set to 100%. Levels were checked for peaking, no peaks. You may hear some hiss when hearing the EQ'ed version, this is due to having to play my music at a lower level than usual since it was late at night. If you perform your own tests with louder sound, your results may be better.
BMPCC - RAW Audio: dropbox.com/s/v13ditom3i4anj1/BMPCC%20-%20RAW%20Audio.mp3?dl=0
BMPCC - High Freq Restoration: dropbox.com/s/u8xechtqtkmcpai/BMPCC%20-%20High%20Freq%20Restoration.mp3?dl=0
Note: The audio recorded was in a quiet room, with my audio system about 2 feet away from the BMPCC microphones, playing some music. The sound you hear is the microphones picking up ambient audio, and sound from my audio system speakers.
The fix I applied took about 5 minutes in post. Creating a preset after tweaking would make it even faster. As always, you are encouraged to make your own tweaks and see if you can rid some of those HF beeps as well. I'm sure given more time, I (or anyone else who's experienced in audio post-production) could make better tweaks to the audio and make it 99.999 better.
I hope that this information could potentially help people with BMPCCs who may need to record using the built-in microphones for whatever reason needed. It surely helped me, and I plan to actually use the built-in microphones to see just how far I can take them when creating films.
This is my first post on the forum, as I've been an avid watcher/checker here and the tips and advice from you all have been an amazing help and value to my usage of BM products. I wanted to post my first tip to everyone out there who has a Blackmagic Pocket Cinema Camera, and *may* want to use the internal mics for whatever reason.
Also, if this all seems TL/DR, or obvious, I apologize. I only intended to inform and inspire. Cheers!
Perhaps someone on here has already posted about the internal mics and outboard fixes that make the BMPCC a great usable solution for audio. As an audio engineer myself, I wanted to dig in deeper into the BMPCC's recording system and shed some light on my findings.
So I've seen many posts here (and everywhere else online) where users speak about the BMPCC's internal mics, and how they are very bad for recording anything usable. That got me to thinking... Why is that?
I started by recording a RAW video, all settings set to maximum quality, and audio settings to their defaults, using the Internal microphones, so that I could grab the unaltered WAV file for analyzing. After transferring to the computer, what I heard was just... YUCK!
I loaded up my favorite DAW, and opened a spectrum analyzer. These were my findings:
RAW Audio coming from the BMPCC is recorded at 48,000KHz, 2 Channel (Stereo), encapsulated as an uncompressed 'WAV' file. Pretty impressive sampling rate, two channels of audio, and should be able to include enough data for the high-end frequency spectrum, right? Well...
It seems that Blackmagic have placed a Lo-pass filter on their final output stage, set to about 4.00KHz, rolling off ALL of the audio data from 4KHz and above, with about a -40db reduction in volume.
I intended to check if this frequency range of audio was restorable in post. I loaded a few instances of 8-band Equalizers, and started applying a boost roll-off of frequency ranges from 4KHz, all the way to 20,000KHz, to keep things linear and smooth. The problem was, one instance of an EQ was not enough to bring up the gain in that range to the audible level yet. So I added another EQ with duplicated settings to the chain.
After some further tweaking... Success! The highs were THERE and equalized! The data is actually in the file, all being recorded perfectly! So why was it that Blackmagic placed this filter there? I kept listening... and I found out why.
There seems to be a bit of high-frequency interference at a few bands of the spectrum up there, always at the same spots in the analyzer. This is due to the very complex circuitry involved in the capturing of video through the lens, the sensors, and various other chips and ICs that create these high-pitched noises. No problem, I applied about 3 notch filters onto my EQ's, honed in on the exact frequency that the noises were being emitted from, and applied a precise cut to them.
The resulting audio when A/B'ed against original file was just amazing. Crisp highs, great mids that were already there, and I'd say a decent low frequency range being captured as well. All from the built-in microphones! Now, I know... this may be extra work that people would need to do just to get a better recording out of some built in microphones when there are surely better outboard alternatives out there. But I figured I'd give it a shot, and it worked.
I have uploaded a test recording of the audio unaltered, and the audio processed using my above-mentioned EQ chain. WAVs needed to be converted to MP3s to save space on the upload. Since recording from the microphone, the only setting that applies is 'Microphone Input' on the BMPCC. I had mine set to 100%. Levels were checked for peaking, no peaks. You may hear some hiss when hearing the EQ'ed version, this is due to having to play my music at a lower level than usual since it was late at night. If you perform your own tests with louder sound, your results may be better.
BMPCC - RAW Audio: dropbox.com/s/v13ditom3i4anj1/BMPCC%20-%20RAW%20Audio.mp3?dl=0
BMPCC - High Freq Restoration: dropbox.com/s/u8xechtqtkmcpai/BMPCC%20-%20High%20Freq%20Restoration.mp3?dl=0
Note: The audio recorded was in a quiet room, with my audio system about 2 feet away from the BMPCC microphones, playing some music. The sound you hear is the microphones picking up ambient audio, and sound from my audio system speakers.
The fix I applied took about 5 minutes in post. Creating a preset after tweaking would make it even faster. As always, you are encouraged to make your own tweaks and see if you can rid some of those HF beeps as well. I'm sure given more time, I (or anyone else who's experienced in audio post-production) could make better tweaks to the audio and make it 99.999 better.
I hope that this information could potentially help people with BMPCCs who may need to record using the built-in microphones for whatever reason needed. It surely helped me, and I plan to actually use the built-in microphones to see just how far I can take them when creating films.
