....any insight into that?
2 interlaced fields = 1 frame
manufacturers often confuse in their 'papers':
30fps could refer to 60i or 30p
mpeg4 is an intra-frame encoder - each frame is compressed independently of the others; should allow an 'easier' processing than inter-frame compressors such as AVCHD.
but intra-frame compression results theoretically in bigger (but 'better') files; therefor, in consumer cams, bit-rate is lowered = less quality. plus, a modern Mac handles AVCHD, because it converts into an intermediate, for editing optimized codec.
no advantages using mpeg4.
A look on the Canon website reveals the answer. Use AVCHD for highest quality. Use MP4 if you need something quick and dirty to put on YouTube or Facebook with no conversion and no editing. The highest quality will be AVCHD at 24Mbps.
The VIXIA HF M50 camcorder gives you the flexibility of dual codec recording, allowing you to record in AVCHD or MP4 format, so you can pick the format that best suits your needs. AVCHD's higher bit-rate and finer resolution will yield the highest quality video for viewing on an HDTV or archiving to Blu-ray™. And for use with today's most typical video applications, the camcorder lets you record in MP4 format, too. MP4 format produces files you can share right away - with no need for conversion. Video is immediately available to upload to social networking sites like Facebook™ or YouTube™, view on an iPhone™, iPad™ or iPod Touch™.
2 hours 20 minutes
1 hour 25 minutes
FXP (17Mbps) - Allows 1920 x 1080 recording:
MXP (24Mbps) - Allows 1920 x 1080 recording: