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Patrick Cooper

Locating the bitrate of a clip

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This might sound like an unusual query. Is there any free downloadable software that could tell me the bitrate of individual clips? The reason I'm asking is that I have a Panasonic G7 that shoots 4k video and when I right-click on Properties - Details within Windows for a clip made with this camera, I get virtually no information at all. It's mostly blank. Certainly no bitrate revealed or hardly anything else. With Shotcut software, I can find out properties of individual clips but there's nothing about bitrate.

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3 hours ago, Patrick Cooper said:

This might sound like an unusual query. Is there any free downloadable software that could tell me the bitrate of individual clips? The reason I'm asking is that I have a Panasonic G7 that shoots 4k video and when I right-click on Properties - Details within Windows for a clip made with this camera, I get virtually no information at all. It's mostly blank. Certainly no bitrate revealed or hardly anything else. With Shotcut software, I can find out properties of individual clips but there's nothing about bitrate.

According to the G7 manual, shooting in 4K mp4 at 24fps or 30fps is at the bitrate of 100mbps. I don't know why the properties don't show in windows.

 

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VLC will do the same thing.

Tools-> media information or CTRL+J (CMD+J on a mac)

It updates to show a realtime average of the bitrate achieved. It's normal for this not to be entirely constant.

P

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16 hours ago, Phil Rhodes said:

Where were you looking?

Just where you said, VLC, tools, media information on a PC. See the attached screenshot. The VLC tabs don't show the Mbps. The Quicktime Movie Inspector shows 57.54 Mbps.

kbps2.jpg

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Hm, that's odd. I don't see many standard-definition DV files anymore, and the ones I have are 25fps 720x576 4:2:0 PAL-style files, but it works for me in VLC 2.2.4. You generally have to let it play for a few seconds to establish some data.

Oh, edit - I wonder if this is some strangeness with type 1 or type 2 DV-AVI files. There was some oddness with those back in the day but I can't see why it would affect this.

vlc_dv_bitrate.thumb.png.08f4322784634ad2f6fd74f196f24d47.png

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7 hours ago, Phil Rhodes said:

Hm, that's odd. I don't see many standard-definition DV files anymore, and the ones I have are 25fps 720x576 4:2:0 PAL-style files, but it works for me in VLC 2.2.4. You generally have to let it play for a few seconds to establish some data.

Oh, edit - I wonder if this is some strangeness with type 1 or type 2 DV-AVI files. There was some oddness with those back in the day but I can't see why it would affect this.

vlc_dv_bitrate.thumb.png.08f4322784634ad2f6fd74f196f24d47.png

I tried running it on VLC for 4 minutes and then checking the media info, and still no bitrate

data. But to confuse things even more, the Windows explorer shows different info than the  Quicktime Movie Inspector. Quicktime says 640x480 pixels, 57.54 Mbps, Windows Explorer says 720x480 pixels, 29.87 Mbps (29874 Kbps). So who knows what it actually is.

kbps-2.jpg

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The 640-wide resolution is the display resolution, while 720 pixels per line are encoded in the file. Standard-definition frames are not encoded with square pixels. If that seems crazy, the design goal was that they should closely match the amount of information that could reasonably be encoded in an analogue video signal. An NTSC picture is 480 lines high, that's a mathematical certainty, but it could actually encode rather more information per inch across each of those lines. Notice that 640/480 is one and a third, which is precisely equal to the 4/3 screen shape, whereas 720/480 isn't. The player is scaling the image for display, and that's correct behaviour.

Where it's getting that bitrate from I have no idea. All types of DV should be about 25 megabits. Some types of AVI file duplicate the audio data for DV files, for complicated technical reasons, which would explain some disparity, but not that much. I wonder if it's doubling the frame rate to approximate roughly-60 field interlaced video and that's somehow causing it to double the data rate. It's not right either way.

P

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