Canon HF G30: which of AVCHD and MP4 gives best quality?

[fvisagie]

Hi All,

The Vigria/Legria HF G30 is my first foray into the world of HD camcorders and I would really appreciate some help. I'll mostly be shooting holiday videos and the odd wedding video for friends and family.

My intention is to archive footage in the original format (hopefully high-quality), and also to write some SD DVDs at times. My existing tools will do the job so no problems with that.

Where I am uncertain is which format to shoot in for best archival quality. The highest AVCHD and MP4 bitrates supported by the G30 are 28 and 35 Mbps resp., both 50p on the Legria. However, there seem to be some differences in encoding format.

MediaInfo reports 28 Mbps AVCHD as follows:

Video
ID : 4113 (0x1011)
Menu ID : 1 (0x1)
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.2
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Format settings, GOP : M=3, N=24
Codec ID : 27
Duration : 18s 680ms
Bit rate mode : Variable
Bit rate : 26.3 Mbps
Maximum bit rate : 26.7 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 50.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.253
Stream size : 58.5 MiB (95%)

35 Mbps MP4 is reported as follows:

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.2
Format settings, CABAC : Yes
Format settings, ReFrames : 2 frames
Format settings, GOP : M=3, N=24
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 12s 960ms
Bit rate : 34.5 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 50.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.333
Stream size : 53.3 MiB (99%)
Language : English
Encoded date : UTC 2013-12-12 19:45:56
Tagged date : UTC 2013-12-12 19:45:56
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Although the same profiles and format settings are used, different Codec IDs are reported, AVCHD seems to use VBR and MP4 CBR, and MP4 has a higher Bits/(Pixel*Frame) value.

I don't quite know what to make of this and lack the knowledge and tools to do an objective comparison. Which format do you recommend?

Many thanks,
Francois

[smrpix]

You do have the tools to do an objective comparison: your eyes.

Shoot some test footage with both settings.

Test 1: shoot something static with lots of little details.
Test 2: literally swing the camera back and forth to generate lots of motion

Watch the footage frame by frame to see which produces the most artifacts -- blocking, rainbowing, over-smoothing.

[fvisagie]

That helped, thanks. The 35 Mbps MP4 setting is marginally but noticeably better with both. Slightly sharper with static scenes and a little less blocking and banding with lots of motion.

[glenpinn]

hi, i am just curious why Canon chose to have 2 video modes using 2 different containers and 2 different bitrates in this camera, given its a consumer grade camera.

the MP4 container is 35Mbps and the AVCHD wrap is 26Mbps, and in my experience, there seems to be very little quality gain by shooting in the mp4 container at 35Mbps.

canon shot themselves in the foot with this camera by offering these 2 modes because it bumped the price of the camera up above other similar spec cams that only shoot in AVCHD @ 28Mbps, and personally i would rather shoot at 28Mbps and pay a bit less for the camera, and to me anything over 28Mbps (26Mbps in reality) is of no real benefit and just creates larger file sizes.

each to their own i guess.

[racer-x]

They probably included the mp4 choice to make the Apple people happy. I'm sure it's easier for them to import and work with the mp4 than the MTS...........

[glenpinn]

interesting that it is still h264 but wrapped in different containers, but i understand for playback support, more devices support mp4 than they do mts/m2ts/ts

even i have to convert my m2ts files from my cameras to mp4 for many clients so they can play them via their HD tv or hdd media players because they dont support mts or m2ts files.

some HD tv's wont even play 1080/50p or 60p video regardless of the container, but many will play 720/50p or 60p just fine.