Convert REC to AVI

A legacy editor, media player, or device may require AVI when a DVR has created a recording with the less widely supported REC extension. Conversion can also create a copy for editing or sharing, but the correct method depends on the recorder that produced the file.

What the REC format is

REC is not a single standardized video format. Digital video recorders, personal video recorders, surveillance systems, and proprietary capture software use the extension for different containers and stream formats. Some Topfield and other PVR systems use REC for MPEG-2 transport-stream or program-stream recordings; other devices store a private structure that general media software cannot parse.

The extension does not identify the container, video codec, audio codec, encryption, or recording metadata. A readable REC file may contain MPEG-2 or H.264 video with MPEG audio, AAC, or another audio format. Open it with MediaInfo, or inspect it with FFmpeg's ffprobe, before choosing conversion settings.

What the AVI format is

AVI is a Microsoft RIFF-based container used by older Windows players, editing applications, and hardware. It can contain codecs such as MPEG-4 Part 2, Motion JPEG, DV, and MPEG-2, but an AVI file is not automatically compatible with every AVI-capable program because codec support varies.

AVI is appropriate when a legacy application specifically requires it. MPEG-4 Part 2 produces relatively small files, while Motion JPEG with uncompressed PCM audio is commonly accepted by older editing software but requires much more storage. AVI generally has weaker subtitle and metadata support than newer containers and is usually unsuitable as a web-publishing format.

How to inspect the REC file

1. Make a backup of the original recording. Renaming input.rec to input.avi changes only the filename, not the format.
2. Open the file in MediaInfo and check for a recognized container, video stream, audio stream, frame rate, and resolution.
3. Alternatively run ffprobe -hide_banner input.rec. If FFmpeg reports Invalid data found when processing input or detects no streams, the file may use a proprietary header, encryption, or a recorder-specific filesystem.

Convert with FFmpeg

FFmpeg is the most controllable desktop option when the REC file contains a standard readable stream. Run the command from the directory containing the file:

ffmpeg -i input.rec -map 0:v:0 -map 0:a:0? -c:v mpeg4 -q:v 3 -c:a libmp3lame -q:a 2 output.avi

This creates AVI with MPEG-4 Part 2 video and MP3 audio, a combination supported by many older applications. For MPEG-4 encoding, lower -q:v values generally mean higher quality and larger files; values from 2 to 5 are practical starting points. The libmp3lame encoder must be present in the installed FFmpeg build.

For editing applications that accept Motion JPEG, use a larger but often more predictable file:

ffmpeg -i input.rec -map 0:v:0 -map 0:a:0? -c:v mjpeg -q:v 3 -c:a pcm_s16le output.avi

If the source streams are already compatible with AVI and the target program, try remuxing without re-encoding:

ffmpeg -i input.rec -map 0:v:0 -map 0:a:0? -c copy output.avi

Remuxing is lossless but can fail when the source codec, timestamps, or stream layout is unsuitable for AVI. It can also produce a file that plays in one application but not another, so test the result and use re-encoding when compatibility matters.

Convert with a graphical application

Avidemux can open REC files that contain standard MPEG streams. Select File → Open, choose a video output such as MPEG-4 ASP or Motion JPEG, choose MP3 or PCM for audio, select AVI Muxer under the output format, then use File → Save. Option names vary between Avidemux versions, and MPEG-4 AVC/H.264 inside AVI may not work in older target applications.

VLC can test whether a standard REC recording is readable, but it offers less control over AVI codecs and is not the preferred conversion tool. CloudConvert, Convertio, and Online-Convert can be tested with a non-sensitive REC file, but online services usually accept only files their backend recognizes as standard video. Do not upload private surveillance footage, personal recordings, or copyrighted material unless the service's handling and retention policies are acceptable.

Quality and compatibility limits

• Re-encoding cannot restore quality lost in the original recording. Keep the untouched REC file as the archival master.
• An encrypted recording or a file tied to a particular DVR cannot be converted by FFmpeg, Avidemux, or a generic online service. Export it first with the recorder's own software, firmware, or playback hardware.
• Broadcast recordings may contain multiple audio tracks, subtitles, teletext, interlacing, or discontinuous timestamps. AVI has limited support for these features; the commands above select the first video and first audio stream.
• Use explicit stream mapping and test playback when a particular audio track is required. Copying every detected stream with -map 0 -c copy can fail because AVI does not support every stream type.
• Older AVI software may have file-size limits, especially near 2 or 4 GB. Large recordings may require OpenDML-compatible software or splitting into smaller files.
• Preserve the original frame rate and interlacing unless the destination application requires different settings. Deinterlacing or changing frame rate during conversion can permanently reduce motion quality.