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H.265 and audio bitrate request
273 5 2020-12-2
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chririva
lvl.4

Poland
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Could you add the possibility to use h265 video compression instead of h264? (as the gopro)

Also, the quality of audio is good, but the bitrate is limited to 192kbps.
It's a limit for those who are willing to edit it, hope you are going to increase it because it's a waste of potential and a pain in the ears

2020-12-2
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DJI Gamora
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Hi, chririva. Thanks for reaching out! The DJI Pocket 2 can only record in MP4 (MPEG-4 AVC/H. 264) video format and that current Audio Output would be 48 kHz, AAC but we'll forward your feedback to our developers. After the evaluation of the engineers, significant suggestions or requests will be implemented via the firmware update, app update, etc. For any updates, please stay tuned to the latest news on our DJI official website at www.dji.com or by checking the Release Notes specific for the DJI Pocket 2.
2020-12-2
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fansfe82067d
Captain
Australia
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I suspect the harmonic distortion that can be seen in test tones recorded by the Pocket 2 is coming from the audio encoder - given the very large size of the video files, I wonder whether it would make that much difference if the audio was completely data-uncompressed, in other words, in wave format?  Is that even possible within the mp4 standards?  Or perhaps an uncompressed audio file could optionally be recorded separately, for the user to add to the normal video file in post production?   The basic audio quality of the Pocket 2 would, in my view, justify that.
2020-12-2
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Ray-CubeAce
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United Kingdom
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fansfe82067d Posted at 12-2 13:10
I suspect the harmonic distortion that can be seen in test tones recorded by the Pocket 2 is coming from the audio encoder - given the very large size of the video files, I wonder whether it would make that much difference if the audio was completely data-uncompressed, in other words, in wave format?  Is that even possible within the mp4 standards?  Or perhaps an uncompressed audio file could optionally be recorded separately, for the user to add to the normal video file in post production?   The basic audio quality of the Pocket 2 would, in my view, justify that.

Hi.
As far as I'm aware, the 48kHz  192kbps bit-rate for aac within the MP4 codec is considered 'adequate' for stereo use. More would depend on the quality of the ADCs and microphones used than the bit rate in my opinion. Noise floors of most mics are higher than the ADCs in the Osmo Pocket one for sure. I don't have information on the ADCs for the Pocket 2. They may be the same or better.
The only codec that I know of that allows for uncompressed wav files is AVI and the end file sizes are huge.
H264 and H265 use aac and are limited to 192kbps. At least on all of my NLEs that is the case and they use standard codecs.
mpeg2 does allow for higher audio bit-rates but the codec is much less efficient than aac.

Harmonic distortion as I understand it comes from the sampling frequency as it takes its readings of the height of the waveform and produces a curve between readings which may be different to that of the actual waveform. So the higher the frequency of the sampling rate, the closer the points are produced and the plotting of the waveform curve becomes closer to that of the original signal.

Ray.
2020-12-3
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fansfe82067d
Captain
Australia
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Maybe I meant intermodulation distortion.  When I was an audio engineer I got on with the job and didn't worry too much about the theory!!   I will try once more to upload the plots I made of the audio measurements of the P2.  Working the forum photo upload system seems to defeat me.  But to put it in words, when you feed a gliding test tone into the P2 (gliding up), on playback, you hear more than one tone going up, and other tones going down.  Not a good outcome.  And yet in real-world situations, the P2 audio sounds just fine.

[Edit - I've now managed to upload my audio test charts and have created a new thread for the purpose.]

2020-12-4
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Ray-CubeAce
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United Kingdom
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fansfe82067d Posted at 12-4 01:57
Maybe I meant intermodulation distortion.  When I was an audio engineer I got on with the job and didn't worry too much about the theory!!   I will try once more to upload the plots I made of the audio measurements of the P2.  Working the forum photo upload system seems to defeat me.  But to put it in words, when you feed a gliding test tone into the P2 (gliding up), on playback, you hear more than one tone going up, and other tones going down.  Not a good outcome.  And yet in real-world situations, the P2 audio sounds just fine.

[Edit - I've now managed to upload my audio test charts and have created a new thread for the purpose.]

Hi.
Try making the charts using different wave forms. Sine, Saw, and square.and you should see different results at different sampling frequencies. It also shifts the sub harmonic distortion into different band areas with a sampling frequency of 192kHz possibly being the most acceptable to our hearing for those with equipment sensitive enough to reproduce the results accurately. How much of this we actually hear compared to what is seen on graphs or measuring equipment is debatable depending on the state of an individuals hearing.
The sampling frequencies that were selected for each video codec was arrived at by the consortiums at the time responsible for their development  and limited by the tech available at the time. Early ADCs and DACs generated massive amounts of heat and needed huge heat sinks. My first Philips CD player had huge heat sinks but eventually the DACs blew up with an audible bang. Things had improved by the time DVD and digital video recording came along and the main reason the 48kHz sampling rate is used today for most video codecs. Again it relied on the state and capability of the hardware available at the time. Sometimes new specifications appear in competing markets but which is eventually adopted is down to who wins the largest market share.
I was also a studio recording engineer at Leeward Sound Studios in Soho London during the later half of the 70s producing radio and TV commercials. Those were analog days though, not digital.
Ray.
2020-12-4
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