3G2 to RM Converter

3G2 to RM: Two Dead Formats That Happen to Fit Each Other

.3g2 is the 3GPP2 multimedia file format, specified in 3GPP2 C.S0050 and recorded by CDMA2000 handsets — the Verizon- and Sprint-era phones that predated everything shooting MP4. .rm is RealMedia, RealNetworks' container from the dial-up streaming years. Neither has a future, and this page exists for the narrow case where an archive index, a playlist or an old RealPlayer-based system needs the .rm wrapper specifically.

What makes this pairing unusually painless is the size of the source. RealVideo 1.0 and 2.0 are 1990s standard-definition encoders with real, hard limits on frame size — limits that make converting HD footage to .rm awkward and sometimes impossible. A phone clip from 2005 sails under every one of them.

Why the RealVideo Limits Do Not Bite Here

RealVideo 1.0 and 2.0 impose two constraints the pipeline has to work around. Frame width and height must both be multiples of 16, and the encoder refuses to start at all on a frame containing 4,096 or more 16 x 16 macroblocks — about 1.05 megapixels. We checked that boundary directly: 1344 x 768 (4,032 macroblocks) opens the encoder, and 1024 x 1024 (4,096) fails outright.

Now look at what a .3g2 actually contains. Clips of that generation were almost always encoded with H.263, which accepts only five picture sizes, or with MPEG-4 Part 2 at similar dimensions:

Every one is already an exact multiple of 16, so nothing gets rounded away, and all are far below the macroblock ceiling. For everything up to VGA that makes .3g2 the rare source where Keep original — the preselected resolution mode — is genuinely safe rather than a trap. The one exception is 4CIF: at 704 x 576 both axes sit above RealVideo's 640 x 480 ceiling, and because each axis is clamped separately the frame comes back 640 x 480 with its proportions altered. Pick a Preset Resolution for those, which scales proportionally.

How to Convert 3G2 to RM

1. Upload Your 3G2 File: Drag the .3g2 onto the page or click "Add Files". .3gp files are accepted here as well, since they are the GSM-side sibling of the same container. Several clips can be queued with one set of settings.
2. Choose Video Codec and Audio Codec: Video Codec lists RealVideo 1.0 and RealVideo 2.0, opening on RealVideo 1.0. Audio Codec lists AAC, AC3 and RealAudio 1.0 — choose deliberately rather than accepting whatever is showing, because two configuration rules both claim the RealMedia target and the preselection is ambiguous.
3. Set File Compression and leave Video resolution alone: File Compression offers Quality Preset, Specific file size, Constant Bitrate, Constant Quality and Constraint Quality. Video resolution opens on Keep original, which is the right answer for a phone clip — there is nothing to gain by scaling a QCIF frame. Trim can be switched from Unchanged to Time Range with a Start time and a Duration.
4. Convert and Download: Click Convert and save the .rm. Files are uploaded over an encrypted connection, re-encoded on our servers and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public.

What Changes on the Way Across

Note the last row honestly: this conversion does not make the file more playable. Both formats need the same class of desktop player. It changes the wrapper and the codec inside, which is what an ingest check or a legacy index cares about, not what a viewer cares about. If your goal is a clip that opens on a phone or in a browser, 3G2 to MP4 is the conversion you want instead.

The Audio Choice, and One Coincidence Worth Knowing

Phone clips of this era carry narrowband speech: AMR narrowband runs at 8 kHz in mono, and the CDMA vocoders that .3g2 also supports are built for the same job. RealMedia's own RealAudio 1.0 is likewise fixed at 8 kHz mono — it was RealNetworks' dial-up voice codec — so for once the sample rate and channel count of the source and the target line up exactly, with no resampling and no downmix.

That does not make it the best choice. RealAudio 1.0 is a 14.4 kbit/s codec, and your audio has already been through one lossy narrowband encoder; putting it through a second one of the same vintage is audibly rough. AAC is the sensible default and will reproduce a speech track far more faithfully at a similar size. Pick RealAudio 1.0 only when the receiving decoder genuinely handles nothing else, and AC3 only when the destination is an AV receiver expecting Dolby Digital.

Whatever you choose, the original audio bytes cannot be carried through untouched. AMR and the CDMA vocoders are decode-only in any general-purpose toolchain, so the track is always decoded and re-encoded.

Frequently Asked Questions

Can I keep the H.263 video instead of re-encoding it?

No. RealMedia carries RealVideo, and the two RealVideo codecs this page can write — 1.0 and 2.0 — are separate codecs from H.263 even though they descend from the same family. There is no stream-copy path anywhere on this page, so the video is decoded and a new RealVideo stream is encoded every time. That costs one generation of lossy compression on a source that is already heavily compressed.

RealVideo 1.0 or 2.0 — which should I pick?

RealVideo 2.0 (RV20, the "G2" generation) is the more capable of the two and the better choice whenever the target decoder supports it, which anything from RealPlayer G2 onwards does. Pick RealVideo 1.0 only when you are matching an existing archive that is uniformly RV10, or feeding something older than G2. At the tiny frame sizes involved here the visible difference is small either way.

Will the file get bigger?

Quite possibly, yes. A .3g2 was encoded to survive a 2000s mobile network, so its bitrate is already extremely low, and RealVideo 1.0 is not a more efficient codec than the H.263 or MPEG-4 Part 2 that produced it. Watch the Quality Preset in particular: because RealVideo has no CRF mode, the preset works by multiplying the source clip's bitrate, and the preselected Very High rung asks for 1.32 times what the source used. Choose Medium (0.9x) or below if size matters, or set an explicit Constant Bitrate.

Why does the Max bitrate box under Constraint Quality do nothing?

Because RV10 and RV20 accept a target bitrate or a quantiser value and nothing else — they have no VBV buffer model — so the maximum-rate and buffer-size arguments are stripped before the encode runs. The quantiser half of Constraint Quality still applies. If you need a genuine rate ceiling on an .rm, use Constant Bitrate, which the encoder does honour.

Is the Constant Quality number a CRF like on an MP4 page?

No, and the label is misleading. The slider runs 1 to 31 and opens at 5, which is an MPEG quantiser scale where 1 is the best quality and 31 the worst — the opposite direction from a CRF number. On an H.264 page the same control runs 16 to 51 and behaves differently, so a value you are used to typing there will give you a very poor-looking RealVideo file here.

My file is .3gp, not .3g2. Does that matter?

Not for this conversion. They are sibling containers built on the same ISO base media file format — .3gp is 3GPP's version for GSM and UMTS networks under TS 26.244, .3g2 is 3GPP2's for CDMA2000 under C.S0050 — and this page accepts both. The practical difference is which audio codecs each was allowed to carry, and since the audio is being re-encoded anyway, it makes no difference to the output. 3G2 to 3GP exists if you need to move between the two directly.

Will the clip play in a browser after converting?

No, and it did not before either. No browser has ever decoded RealVideo, and no current browser decodes H.263 in a 3GPP2 container either. Both formats need VLC, mpv or something else built on FFmpeg. If you want a file that plays on a phone, a browser or a TV, convert to 3G2 to MP4 — H.264 in an MP4 opens essentially everywhere and will be smaller than the RM at the same quality.

My clip is rotated the wrong way after converting. Why?

Phones record with the sensor in a fixed orientation and store the intended rotation as container metadata rather than baking it into the pixels. RealMedia has no equivalent field, so whatever rotation was signalled in the .3g2 cannot be signalled in the .rm. If the source plays upright and the output does not, the rotation was metadata; you will need to fix the orientation before or after this conversion in a tool that can apply it to the picture itself.

Can I convert just part of a long clip?

Yes. Set Trim to Time Range and enter a Start time and a Duration, and only that section is encoded — which is much faster than converting the whole file and cutting afterwards. If you would rather cut before you convert, Video Cutter accepts .3g2 directly and Trim 3G2 writes the result back in the same container.

What happens to my file after the conversion?

It is uploaded over an encrypted connection, re-encoded on our servers, and both the upload and the .rm it produced are deleted automatically after a few hours. Nothing is shared or made public, and there is no sign-up or watermark. Clips from CDMA handsets are small by any modern standard, so neither the transfer nor the encode should keep you waiting long.