******* *** *** ** *********-***** ***** *********** (H.264/H.265), *** ***** **** **** ******* ***** quality ******** *** ********* ************* **** widely, **** ** ********* *** *********** or ***** ****. **** *** ****** in *** ******* **** *** **** resolution ******** ** *** ********* ************* ********* widely ********* ***-**-***-*** *******.
** **** ***** **** *********, **** has ******** ******* **** ** ************* *** answered ***** *** *********:
- **** ** *** **** *.*** ***/** H265 ************ ***** *** **** ****** manufacturer's ******* ********? *** ** **** vary? *** ******** *** ****** *** highest?
- ** ********* *** *.***/*.*** ************ ****** so **** **** ************ *** *** same ***********, **** ****** ******** ****** be ****?
- **** ** *** ****** ** ********* as *.***/*.*** ************/*********** ****** *** ****** for ********* *************?
- **** ****** ** ***** ****** **** ** ***** ********?
**** ** **** ** ***** *** ******* settings **** ***** *************, ******* ************ **** the ******* ******* *********** (*****), **% higher **** *** ************ **** *** lowest ******* *********** (*******):
** *** ****** **** ***** ***** quality *** ********** ********* / ******* use, **** ** * ******** ******.
Key ********
**** *** *** *** ******** **** this ****:
- ******* ******* ************:***** ** *** *****, ******* ******* quantization ** ~**, **** ******* ******* widely, **** ~** ** **.
- *.*** ************ ****** ******* ** *.***:******* ******** *************' *.*** *******, ** found **** ************ *** ************* ******* when ***** *.*** *** *.***, ****** bandwidth *** ******* ***** ***** *.***.
- ****** ********* ******: ** * **** ** *****, ***** from ****** ********** *** ** **** average *** ******** ** * **-** bandwidth ********, ******* ** ************. *** to *** *** * ******* **-*** increase.
- ** *********** ******* *************:** *** ** ************* ******, **** used *** **** ****** *********** *** scale, *** *** ******* ***** (**** as "******") ****** ** ******* ************ levels.
Video *********** ********
************* ***********, *** *** ************* *** to **** ****** ************ ***** ********, is **** *********. ******************* *** *********, *********** ** ******** and *** ** * ****** ****** -**** *** ******* *** *********.
*** ************ ***** ** **********, ********** of **********. ***, **** ** *** cameras **** *** **** **********, ***** compression ****** *** ** **** ********* (see *** ***** ******* / *********** ******** *** **** **********).
**********, *********** ** *.*** *** *.*** is ************ ** * ***** ** 0 ** **, ****** ************, ** shown ** *** ***** *****:
*******, ****** ************* ****** ***** ******** what ************ ****** ***** ******* ***. Instead, **** *** * ******* ** scales *** ****** *******. *** *******, **** is **** ** ************* ***** ** their *********** ******** **:
** * ******, *** *************' ******* ***** **** the **** ********** *** ************* ********* compression ******, *** ********* ******* ***** quality *** ********* ***********.
Average ******* ************: ~**
***** ** ****** ******** ** **+ cameras **** ***** ** *************, ** found ******** ***** ** *** ***** below.
- ******* ******* ************ ***** *** ** with * ***** ** ** ** **.
- ******* ******* ********* ** *** ****** quantization ** *** ******* ****** ** Q20, **** ********* *** ******* ***** at **.
- *** ******* ******* ************ *** *****, approximately *** ** *******.
Terminology ***********
**** ** *** ************* ****** **** terminology ** ****** ***** ****** *** directly ********** ** ***** *************. **** may ***** ********* **** ****** ** standardize ******** ******* ** *** ************ level.
*******, ****** *** **** ********* ****** depending ** *** ************, ****** ******** even **** *********. *** *******, ******* all ***** * ********* *****, ***** and **** **** **** * ******/***** quality **** *********** ** *** ** "1", ***** ********, ****, *** *****, have *** * ******/****** ******* **** compression *** ****** ** "*".
Normalizing ***********
** **** ********** **** ******'* *********** settings ** ******* * ************ ** ~28. **** *** ** ****** *** users ******* ** ********* *********** ******** on ***** *** *******, ****** ** a ***** *** ******* ****** **** the **** ************.
**** **** ***** *** **** ******** of ******* ***** ***** ** ******** adjust *********** ********, ***** *** **** exceptions. For *******, *** ********** ****** *** Sony ******* **** ******* * ***-******** VBR ************** ***** **** *** *** compression *** ******* **** **** * bitrate ****** ***/** ***, **** *********** and ******* **** *******. *** *** report **** *** ******* ******** ***.
Quantization ************* ******* ***** *.***
***** ** *** ***** ** ******** manufacturers' *******, ******* *** ************ ************ ****** were ************* ******* **** ***** **** H.264 *** *.***, ******** ******** **** notably ***** ** *.*** *******, ********* 30-40%. ******* ****** *** *** *.*** / **** ***** ******** **** *** **** ***********.
Compression ****** ** *********
********* ** ******** ******** ** ************ level. ** *********** ****, **** ******** quantization **** * ******** ** *** (highly **********) ** * **** ******* Q28, ******** ** * ***** *********** Q22.
***** ** ***** *****, ** *****:
- Q35 ** ***: Changing quantization from Q34 to Q28 resulted in a 3x-5x bandwidth increase on cameras tested (Axis, Dahua, Hikvision, Panasonic).
- Q36 ** ***: Changing from Q35 to Q22 resulted in drastic increases, ranging from about 5x to 11x, depending on manufacturer.
Smart ***** ******
*** **************** ********* ***** ***** **** when ***** ****** *** ****** *** or *** *********. ** ******, ***** they ****** ************ *********** ***** ** objects ** *** ***** ******* ** adjusting ** ** *** ****** *****, smart ****** *** **** *********, ** not **********, ** ***********.
************, ************ ****** ** ***** ***** cameras *** ********* **** ****, **+, since **** ** **** ****** ** regarded ** ****** ********** *** ********* more ****** **********, **** **** ****** objects ********* ******* ** ***** ***********.
*** *******, ****, *****, *** ******* ********* to ***** ****** ******* ** *** tests, *** *** ***** ******** ** or ****** ************:
******* ****** *** *** ***** ***** ***** *** **** ******* ** ***** ******** and ******* ******.
Setting *********** *** ********* *******
***** ** **** *********** ******** *** each *************' *******, **** ***** ********* defaults *** *************.
*******
******* ** *** ** *** ************* to ******** *** *** ************ ***** in ***** *** *********. ************ ** adjustable **** ** ** **, ********** to **.
********
********'* *********** ******** *** ** ******* under *** *********** *** ***** **** tab ** ***** *** **, *** it **** * ******* ****** ** "1" (****** ***********) ** "**" (******* compression). Quality ******** ** "*", ***** ** quantization.
****
**** ********* **** *** ********* *** interfaces, ** **** ** ***** ******* have *** *** ************ ** ******** ***** ***** **. **** *** *** *** *** UIs ******* ** *** **** ********: ** compression. *** *** *** ********* **** a ******/****** *****:
***** *** *** ********* ****** ****** free *****:
*****
*****'* ***** ***** ***** ************ ** P-frames, **** *-****** ******* ** **** by * ******** ****** ("*/*-***** ***** QP" *****). ** *********** ** ******* 28Q, ***** ****** *** "***. *-***** QP" ** **, *** *** */*-***** delta ** *.
*****
*****'* *********** ******** *** ***** ** the ***** ***, *** *** "*******" can ** *** ******* "*" (**** compression) ** "*" (***** ***********), **** 2 ******** ** ~** ************ ** most models ******.
*********
*********'* *********** ******** *** ***** *** video/audio ***, ** * ***** ** "******" (**** compression) ** "*******" (***** ***********), ********** to "******." ***** ** *** ***** of ******** ********* ******, "******" ******* to ~***.
******/*******
*** ***** ****** ******* ** *** include *** *** ** *** *********** of *** ******, **** **** ******* and ************ *******. *** **** *******, see *** ****** **** *** ******* ******** ***.
***** ****** (******* ***/****) ******* *********** on * ***** **** "**** (*)" (***** compressed) ** "***** (**)" (**** **********), defaulting ** *. ***** ****** ****** be *** ** ~** ** **** scale *** ******* ** ************.
*********
** ***** ** ****** ***** ******* of ********* ******, ***** ****** *** transmission ******** ** *** (******** ** Frame ****). ***** ******* ** ******** on * ***** ** *-* (***** Fine ** ***), ********** ** * (Normal), **** * ******* ************ **.
**** **** ** ******* ******, *********'* new ******* ****** **** *** **** models ***** ********* ** *.***, ***** below.
****
** **** ***/*** *** ***** ***** ********, *********** ** *** ** *** "Image ******* *: ******** ****, ***** ranges **** "*" (**** **********) ** "10" (**** **********), ********** ** * (roughly ***).
**** **** ******* ** ******, ****'* 7th *** ******* ** *** ***** compression ** ** ***** ** * set *****. *** **** *** ******* ******** *** *** **** *******.
*******
******* ******* **** ***** ******* ** a ****** ******* **** ****** "*******" to "*** ****", **** ** ****** to ******** ***** * *****. *** slider ****** ** *** ** ~*/* of *** *** ****** *** **** for ~***.
*******
*******'* *********** ******* ** ***** "****** Quality", ***** *****, **** * ***** of "******" (*****) ** "*********" (****). "Good" ****** ** **** *** ************ ~28.
Test ********
***** ******* **** ******, *** ****** be **** ** ****** *** * ********* ** **** quiz.
[****: **** ****** *** ********** ********* in **** *** ************* ******* ** 2017]
Comments (14)
Undisclosed Manufacturer #1
Great report! Can you elaborate on the impact of altering P frame interval (or some say, I frame interval or keyframe interval)? Is there any significant relationship between keyframe interval and quantization? Clearly the shorter the time between P frames, the higher the bandwidth but what are the other impacts on the video? It's another opportunity for confusion on which way the scale goes and its impact on quality and bandwidth. Thanks!
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Sergey Bystrov
11/27/17 09:13pm
Besides quantization levels, final image quality would depend on:
- spatial filter
- temporal filter
- motion vectors search( a type of macroblocks)
- motion vectors search( accuracy: pixel, half a pixel, quarter pixel etc )
- macroblocks type selection
- CBAC vs CAVLC
- bitrate control( how well does it handle changes)
- etc
Quantization parameters is a small part of the overall equation, and making some conclusions based on it is likely misleading.
If I would explore how advanced codecs are from different vendors, I would analyze other parameters as well: so you can see that this vendor uses macroblocks of such type, motion vectors of such accuracy etc... I know nobody would be interested in reading:-)
But only real criteria of image quality/bitrate is subjective "I like it more" or "I like it less", not quantization by itself.
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Ashley Schofield
Great report, but curious to know the firmware versions tested of each camera.
Cheers
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Franky Lam
11/28/17 01:55am
Details report and end-user must always care about the bandwidth and storage issue. But Chinese Band Distributor always hidden this issue to the end-user.
Thank you, IPVM.
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Undisclosed End User #4
Thank you for another great report IPVM. Question, how did you measure image quality? Did you use some type of tool or did you just manually review the video? Also what tool did you use to watch the video? The viewer inside the camera, another third party tool (ie- VMS)? These details can affect the perceived quality, hence I'm asking. Thanks!!!
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Undisclosed Integrator #5
Well done as usual.
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