MyMediaTools

Convert RM to MTS — Free Online Tool

Convert legacy RealMedia (.rm) files to MTS (AVCHD), re-encoding the video with H.264 (libx264) for modern camcorder and broadcast compatibility. This is ideal for rescuing streaming-era RealMedia archives and bringing them into a format supported by professional video editors and Blu-ray workflows.

FFmpeg Command

Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg

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Estimated output:

Conversion Complete!

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How It Works

RealMedia files typically contain MJPEG video and AAC or MP3 audio encoded with RealNetworks' proprietary streaming-optimized tools. Because MTS (AVCHD) requires H.264 or H.265 video inside an MPEG-2 Transport Stream container, the video must be fully re-encoded — there is no stream-copy shortcut here. FFmpeg decodes the MJPEG video frames and re-encodes them using libx264, applying a CRF of 23 (a perceptually good balance of quality and file size). The audio stream is transcoded to AAC at 128k bitrate, which MTS fully supports. The output is wrapped in the MPEG-2 Transport Stream (.mts) container, making it compatible with Sony and Panasonic AVCHD workflows and most professional non-linear editors.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — the open-source multimedia processing engine that powers both this browser-based tool (via WebAssembly) and the local desktop command.
-i input.rm Specifies the input RealMedia file. FFmpeg will detect the container format and attempt to identify and decode the embedded MJPEG video and AAC/MP3 audio streams inside the .rm file.
-c:v libx264 Sets the video encoder to libx264, re-encoding the MJPEG frames from the RealMedia source into H.264, which is the standard video codec expected in AVCHD/MTS files and widely supported by professional editors.
-c:a aac Encodes the audio stream to AAC, which is the default and most compatible audio codec for MTS containers. If the source .rm already contains AAC, FFmpeg will still transcode it to ensure it meets the output container's stream requirements.
-crf 23 Sets the Constant Rate Factor for libx264 to 23, which is the default and represents a good balance between file size and perceptual quality when transcoding from MJPEG RealMedia sources. Lower values (e.g., 18) yield higher quality at the cost of a larger MTS file.
-b:a 128k Sets the audio bitrate to 128 kilobits per second for the AAC output stream. This is a standard bitrate for stereo AAC audio and is sufficient for most speech and general-purpose video content originally streamed in RealMedia format.
output.mts Specifies the output filename with the .mts extension, which tells FFmpeg to wrap the encoded H.264 video and AAC audio in an MPEG-2 Transport Stream container formatted to the AVCHD specification.

Common Use Cases

  • Archivists converting late-1990s or early-2000s RealMedia streaming recordings into a modern, editable AVCHD format for long-term preservation.
  • Video editors who received legacy .rm files from a client and need to import them into Sony Vegas, Adobe Premiere, or other NLEs that natively handle MTS/AVCHD.
  • Broadcasters or media librarians migrating old RealMedia news or documentary footage into a broadcast-compatible transport stream format.
  • Educators or trainers who recorded online lectures or webcasts in RealMedia format and want to repackage them for playback on modern camcorder-compatible devices.
  • Home users who want to combine old RealMedia family videos with footage from a Sony or Panasonic AVCHD camcorder into a single consistent format for editing.

Frequently Asked Questions

Yes, some quality loss is unavoidable because this conversion involves a full transcode at every stage. The original MJPEG video in the .rm file is decoded and re-encoded with H.264, which introduces generation loss. However, H.264 at CRF 23 is generally quite efficient — in many cases the output will look comparable to or cleaner than the original MJPEG, since H.264 handles motion and smooth gradients better than MJPEG at similar bitrates. The original RealMedia files were often highly compressed for streaming, so the perceptible difference is usually minimal.
Some .rm files contain only audio (RealAudio streams) rather than video, which is common for music or radio content distributed via RealNetworks in the late 1990s. If your source file is audio-only, FFmpeg will produce an MTS file without a video stream. You can verify this by inspecting the file with ffprobe before converting. If video is present but missing after conversion, the source may use an unsupported RealVideo codec variant that FFmpeg cannot decode.
Neither RM nor MTS supports embedded chapter markers in a meaningful way for this workflow. RealMedia did have a limited subtitle/SMIL scripting layer, but FFmpeg does not extract these as subtitle streams during conversion. MTS does technically support subtitles in MPEG-2 Transport Stream, but the FFmpeg command on this page does not include a subtitle mapping flag, so any subtitle-like metadata in the source .rm will be dropped. For subtitle preservation, a container like MKV or MP4 would be a better target.
The video quality is controlled by the -crf flag. Lower CRF values mean higher quality and larger file sizes — CRF 18 is often considered visually lossless for H.264, while CRF 28 produces noticeably smaller files with more compression. For example, to get higher quality output from your .rm source, change -crf 23 to -crf 18 in the command: ffmpeg -i input.rm -c:v libx264 -c:a aac -crf 18 -b:a 128k output.mts. The valid range for libx264 is 0 (lossless) to 51 (worst quality).
Yes, you can substitute libx265 for libx264 in the command to get better compression efficiency at the same perceptual quality. Replace -c:v libx264 with -c:v libx265 in the FFmpeg command. However, be aware that H.265 in an MTS container has limited compatibility — many AVCHD-based editors and devices expect H.264 in .mts files, so H.265 MTS may not import correctly into all workflows. H.265 is more useful if you are targeting a future-proof archive rather than immediate AVCHD playback compatibility.
The command shown converts a single file, but you can adapt it for batch processing on your desktop. On Linux or macOS, use a shell loop: for f in *.rm; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.rm}.mts"; done. On Windows (Command Prompt), use: for %f in (*.rm) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.mts". The browser-based tool processes one file at a time, but the FFmpeg command is especially useful for large collections or files over 1GB.

Technical Notes

RealMedia (.rm) is a proprietary container from RealNetworks that was dominant in early internet streaming but is now largely obsolete. FFmpeg supports decoding common .rm variants (MJPEG video, AAC/MP3 audio) but does not support encoding to RealMedia, and decoding support depends on the specific codec version embedded. MJPEG — the most common video codec found in .rm files this tool targets — stores each frame as an independent JPEG image, making it easy to decode but inefficient compared to modern inter-frame codecs. The output MTS container is based on the MPEG-2 Transport Stream specification (AVCHD standard), which mandates specific stream structures expected by Sony and Panasonic hardware and editing software. Metadata such as title tags or creation dates embedded in the RealMedia container will generally not be mapped to MTS output, as the two formats have incompatible metadata schemes. File size after conversion can vary significantly — RealMedia files were often aggressively compressed for low-bandwidth streaming, so H.264 output at CRF 23 may actually be larger than the source while appearing visually similar or better. Multiple audio tracks and subtitles are not carried over in this conversion.

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