Hi, All.
I hope that´s the most appropriate forum here, since it seems to be the more technically skilled.
Most of 4-channel dash cam recorders claims a 30FPS frequency, some with more than that, other with at least 15FPS. I couldn´t find a vehicular system that recorded at very low rates as 2 FPS.
Why I mentioned that?
I´ve got a ASF format video file (extension WMV) to analyze and it presents a new scenario each 0,5s (2 Hz). This is allegedly an original video made by a dash cam recorder, (supposely) with no edition nor conversion. In this file, there´s a sudden jump in time according timestamp, 16 seconds, just few seconds before and some after an accident, strongly suggesting that there was an intentional cut. I don´t know yet what´s the dash cam recorder maker nor product type and this information may take long time to get. Thus, I´m trying to speed up this study.
So, if there is, or there was, a 2-FPS system, it would be enough to make such a file but, as I mentioned above, dash cam recorders on the market works with at least 15FPS, so image refresh would happen each 67ms, much faster than that 500ms that can be seen on that WMV file I mentioned.
This WMV file has a 30FPS rate, according to the specific field in the file header (ASF format) and has a 15-frame extent for each scene, sometimes 7 frames. With a 30FPS specification in the file header and 15 frames per scene, yes!, you see a movie that changes scenes each 0.5, or 2 scenes per second. That´s makes sense.
But what DOESN´T make sense is a movie (allegedly original) that shows 2 images per second has been recorded with 14 repeated frames (1 frame with a useful image and 14 more frames with the same image), this way wasting media room and processing time.
So, I´ve got 2 hypothesis, and that considers that this WMV file is not the original one:
1) the original video was 15, 30, whatever (much) more than 2 FPS, but was converted to a file taking frames with a 14-frame interval. In other words, taking 1 frame and skipping 14. Most dash cam records on the market records at a 30FPS rate, some at 15FPS, others at more than 30FPS.
2) the original recording was really done with a 2 FPS rate (although I don´t know if some dash cam recording system allows such recording rate) and a new file was created after the original has been edited, and saved with a different quality, that increased FPS (thus, resulting the replicated frames)
Since I´m not a dash cam expert, I ask you to help me to understand this case.
Regards!
I hope that´s the most appropriate forum here, since it seems to be the more technically skilled.
Most of 4-channel dash cam recorders claims a 30FPS frequency, some with more than that, other with at least 15FPS. I couldn´t find a vehicular system that recorded at very low rates as 2 FPS.
Why I mentioned that?
I´ve got a ASF format video file (extension WMV) to analyze and it presents a new scenario each 0,5s (2 Hz). This is allegedly an original video made by a dash cam recorder, (supposely) with no edition nor conversion. In this file, there´s a sudden jump in time according timestamp, 16 seconds, just few seconds before and some after an accident, strongly suggesting that there was an intentional cut. I don´t know yet what´s the dash cam recorder maker nor product type and this information may take long time to get. Thus, I´m trying to speed up this study.
So, if there is, or there was, a 2-FPS system, it would be enough to make such a file but, as I mentioned above, dash cam recorders on the market works with at least 15FPS, so image refresh would happen each 67ms, much faster than that 500ms that can be seen on that WMV file I mentioned.
This WMV file has a 30FPS rate, according to the specific field in the file header (ASF format) and has a 15-frame extent for each scene, sometimes 7 frames. With a 30FPS specification in the file header and 15 frames per scene, yes!, you see a movie that changes scenes each 0.5, or 2 scenes per second. That´s makes sense.
But what DOESN´T make sense is a movie (allegedly original) that shows 2 images per second has been recorded with 14 repeated frames (1 frame with a useful image and 14 more frames with the same image), this way wasting media room and processing time.
So, I´ve got 2 hypothesis, and that considers that this WMV file is not the original one:
1) the original video was 15, 30, whatever (much) more than 2 FPS, but was converted to a file taking frames with a 14-frame interval. In other words, taking 1 frame and skipping 14. Most dash cam records on the market records at a 30FPS rate, some at 15FPS, others at more than 30FPS.
2) the original recording was really done with a 2 FPS rate (although I don´t know if some dash cam recording system allows such recording rate) and a new file was created after the original has been edited, and saved with a different quality, that increased FPS (thus, resulting the replicated frames)
Since I´m not a dash cam expert, I ask you to help me to understand this case.
Regards!
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