HERE, the developers stated RockPlayer2 is “the best media player on iOS” and “plays everything, playback is fluently, image quality is excelent and it brings so many innovative experiences” (direct quote).
The app is HERE and is free. If the in-filelist and during-pausing ads annoy you, you can remove them via a $5 in-app purchase. (No ads displayed during playback.)
The player is a rather mediocre one when it comes to video playback performance, features and compatibility. However, it has some unique features hardly found in any other player, because of which alone you may still want to give it a try, particularly if you often want to share video clips with your iOS friends without using traditional ways of sharing (DropBox, iTunes transfer etc.). Let's start with the latter.
The player has some unique features certainly worth mentioning.
First, it's able to access the Camera Roll – very few other multimedia players (the ones that do: PlugPlayer, ReplayerHD Pro, Play Any Video Format - PlayerX HD (with very heavy recompression, though), Azul Media Player - Video player for your iPad By Gplex, CineXPlayer – The best way to enjoy your Xvid movies by NXP Software B.V. (this recompresses too)) are able to do so. Unfortunately, you can't import / transfer the videos to your own RockPlayer2 library, including not being able to put them on playlists (which are pretty well supported in the player) and, even more importantly, it's not possible to send them wirelessly (see the section immediately below) to another iDevice running RockPlayer2.
Second, it's able to quickly transfer files between itself running on different iOS devices (even between large- and small-screened ones). The transfer speed is pretty good: I've measured around 1.4 Mbps on my “clean” 802.11g local network between an iPad 3 and an iPod touch 4G. Transferring a file (or sets of files) is very easy: you just select it/them in the file list view and tap the Wi-Fi icon. When there's another iOS device running RockPlayer2 in the vicinity, it'll be listed as a possible receiver. You tap its name; a confirmation dialog is, then, displayed on the other:
If you allow for receiving the files, the transfer starts. You can also see what is being transferred if you tap the Wi-Fi icon again. On the receiver size, two examples: a during-transferring and an after-finishing shot:
This is indeed a VERY good feature and is far faster than, say, iFile's implementation. If you jailbreak and install iFile, you'll also be able to transfer files from any app's Documents directory – even those of, othwerwise, non-transfer-enabled multimedia players. However, iFile uses GameKit and Bluetooth (or, when installed, you can also use the excellent AirBlue Sharing), meaning it'll have about an order of magnitude (!) lower speed. (Also tested between my two devices transferring files using RockPlayer2 around 1.4 Mbyte/s.)
Third, a nice feature also pretty uncommon with other players: the ability to redefine all the on-screen buttons:
Pure playback performance, compatibility
Well, when it comes to playback performance, I need to say I've seen much better players. Playback of more CPU-taxing videos is generally marred by lipsynch issues and there's no way of fine-tuning frame dropping / synchronization to avoid this; the WMV decoder is below-par; subtitles aren't really supported etc. There are (at least) four considerably better, free titles out there delivering vastly superior performance and features, video playback speed/compatibility-wise:
And, of course, the, apart from the lack of Retina 3 screen support, by far the best free player, XBMC (if you jailbreak.)
And, of course, video playback and feature-wise, it in no way can come close to the best of the commercial AppStore video players:
Note that the audio playback support of RockPlayer2 is considerably better than that of video playback. If you're into FLAC, APE, WAV or WV playback (plase see THIS for more info), you might want to check it out.
Also note that the player supports hardware MP4 / M4V / MOV playback. If you stick with that format (and the lack of subtitle support isn't a problem), the (relative) weakness of the video decoders of the app won't be an issue for you but you can still use the goodies of the app (e.g., 10/20-second rewind/fast forward; file sharing etc.).
I've added a near-complete assessment of the player into the chart of my forthcoming all-in-one multimedia player roundup. It's available HERE (LibreOffice Calc format!). Currently, the player is listed in column C. Warning, the chart is still in beta and is, consequently, pretty much messed up. Nevertheless, it already contains a lot of cool info and links.
A detailed assessment of real(!), tested(!) features and performance:
Generic playback-specific, not format-dependent features:
Gesture-based (short) rewind / fast-forward (excellent for watching and controlling video playback during, say, running in the gym; see THIS): -
Adaptive scrubbing (just like that of the stock Videos player): -
Audio format support and performance:
- WMA: only basic format is played back, nothing else
- FLAC: +, all tests passed
- APE: +
- WAV: +
- WV: +
Video format support and performance:
WMV (see THIS): even lowest-res ones are useless; advanced audio isn't supported at all. The video test with the intro was jittery even in the low-res version.
Buck Bunny, 1080p30 full HD:
AVI (MS-MPEG4): a bit stuttering video (AVPlayerHD and the other players with excellent MS-MPEG4 decoders) and quickly desynched audio
TS (DVB recordings with MPEG-2 inside):
1080i60 (US): major desynch issues – the latest version of OPlayer HD (see my quick test report of the latest version HERE) is way better
576i50 (Europe, Finland): doesn't seem to be reading the Widescreen (16:9 vs. 4:3) flag (unlike with the previous, 1080i60 US case): all originally as Widescreen broadcast videos are played back at 4:3. In addition, it's
Camera M-JPEG XGA 15 fps AVI: useless: the colors aren't correctly rendered or rendered at the wrong places
H.264 software decoding (including MKV playback): not as good as AVPlayerHD or other top players.
(Embedded) subtitles (after explicitly allowing them by assigning “T1” to an on-screen button):
SRT (in MKV): -
Embedded VobSub subs: neither MKV nor M4V.
DSP's (see the It's Playing review for more info): nope. The brightness setting (when assigned to an on-screen button and invoked through it) only sets the iDevice's brightness, not that of the video playback.