MJPEG vs MPEG2 vs MPEG4

[John_lin78 0]

Can anyone here tell me the differences between MJPEG vs MPEG2 vs MPEG4 in their recording quality and web transmission speed?

 

Can anyone here also recommend a DVR for each of the above type and give me a rough idea of their prices?

 

thanks.

[rory 0]

Well slowest to fastest in the order you listed.

 

Quality, MJpeg from what I have used is pretty much as clear as Wavelet which is clearer then Mpeg 2 or 4, but takes up more space recording.

 

As for DVRs, depends what your budget is, and amount of camera channels you are looking at. Also whether you want RTOS or PC?

 

Rory

[John_lin78 0]

Thank you Rory, I heard MJPEG has the clearest picture quality among the 3, is that true? How about MPEG4?

 

I understand MPEG4 has better compression so the transmission speed is faster, but does faster speed = sacrifice of picture quality?

 

about prices, say what would you recommend for a 4ch DVR with price range MJPEG > $500, MPEG2 > $1000 and MPEG4 > $2000?

 

Thank you very much.

[rory 0]

Yes, you sacrifice quality for speed. Wavelet has to be the best I have seen, Mjpeg is around the same.

 

Depends if we are talking high end, mid range, or budget DVRs ...

 

4 channel RTOS stand alones?

 

-$500 - Power Tellecomm - Mjpeg

 

-$1000 - Active-Tek / Uriel /Eclipse Nubix - Mpeg4

 

Mpeg4 isnt even in most high end RTOS stand alone DVRs yet ... most are Wavelet, Mjpeg, or Mpeg2.

 

PC based mostly all have choices of Mpeg4, Mjpeg, and Wavelet, selectable.

 

Rory

[Thomas 0]

MPEG-4 can look better at lower bitrates. It all depends on what the encoder is set at. But MJPEG does tend to have the least problems being portable.

[cctv_down_under 0]

The best compression I have seen is MPEG2 after all that is a DVD style compression, obviously it differs to explain the compressions.

 

Wavelet

 

This is an awesome compression mechanism, if you can imagine filming a person doing news broadcast infront of a grey wall, well Wavelet analyses frame by frame, the detailed parts in the frames, for instance, the wall does not move and has the same contoured finish and is flat with little detail, therefore Wavelet wont attend as much detail to the wall but more to the contoured or moving parts of the picture, Wavelet is good for non detailed scenes and in my opinion gives very little loss indeed, when set to little compression it has an awesome result.

 

JPEG

 

Remember when you were a kid and you drew a stick man on every page of the telephone book and advanced his movement one page at a time so that it looked like he was walking, well JPEG is like this.. One single frame at a time, very big on file size but awesome for still pictures, when little compression is done it gives supurb results, however if heavy compression is used or stretching of detail by zooming you will often be dissapointed by JPEG.

 

MPEG4

 

All the rage, Imagine you have a camera in a room which has a pedestal fan that is moving but nothing else in the picture has moved, well ...lets just break that down to frames or 5 still images instead of an AVI type file.. so we have 5 still shots (frames) well the scene (the room) has not changed in any way except the movement of the fan so to save space, MPEG4 will draw the area of movement on the last frame because the rest of the picture has not moved ... another example would be a man walking past a camera that is looking at a house... there is no need to re-draw the house so the man is overlayed onto the previous frame where he was not present and not having to draw that frame will save vital space.

 

in short it means it sort of only records the moving bits and places it on used footage to save space.. aa bit like cuting and pasting an email signature into an email.. you wouldnt type it all again just to add it, you would simply overlay it as the rest had not changed, this makes this very fast for transmition and excellent when you need low bitrates and file sizes.

 

I hope this helps