Free online OGM to DAT converter

OGM files often need conversion when a legacy VCD player, authoring application, or device accepts only MPEG-1 video stored as a DAT stream. The conversion normally requires re-encoding because OGM commonly contains codecs that VCD hardware cannot decode.

What the OGM format is

OGM, or Ogg Media, is an older container based on Ogg that can hold video, audio, subtitles, and metadata. Files commonly contain MPEG-4 Part 2 video with Vorbis audio, although other codecs are possible. VirtualDubMod, OggMux, and older OGM tools created or edited these files; media downloaded or archived before Matroska became common is where OGM is most often encountered.

What the DAT format is

In video workflows, .dat usually identifies the MPEG-1 program stream stored in the MPEGAV directory of a Video CD, commonly as AVSEQ01.DAT. It is intended for VCD players and legacy playback software, not as a general-purpose container. VCD DAT streams use fixed video constraints, typically 352×288 at 25 fps for PAL or 352×240 at approximately 29.97 fps for NTSC, MPEG-1 Layer II audio at 44.1 kHz, and a combined bitrate near 1,411 kbps. The extension alone does not make a file VCD-compliant; the codecs, bitrate, stream structure, and disc authoring must also match the standard.

How to actually convert OGM to DAT

FFmpeg is the most practical desktop tool because it reads OGM and can encode the MPEG-1 video and MP2 audio required by VCD. Check the source streams first:

ffprobe input.ogm

For a PAL-compatible DAT stream, run:

ffmpeg -i input.ogm -map 0:v:0 -map 0:a:0 -target pal-vcd output.dat

For an NTSC-compatible stream, use:

ffmpeg -i input.ogm -map 0:v:0 -map 0:a:0 -target ntsc-vcd output.dat

The -target option selects VCD-compatible MPEG-1 video, MPEG-1 Layer II audio, frame rate, dimensions, bitrate, and muxing parameters. Replace input.ogm with the actual filename and select the target standard used by the player or disc-authoring software. If the OGM contains multiple audio tracks, change -map 0:a:0 to the required stream index.

For a physical Video CD, creating a file with a .dat extension is not the entire authoring process. Test the generated stream, then use VCD authoring software such as VCDImager to create the disc image and place the stream in the required MPEGAV structure. Do not simply rename an OGM file or an arbitrary video file to .dat.

If installing software is not suitable, the conversion can be performed for free on 101convert.com by uploading the OGM file and selecting DAT as the output format.

Quality, compatibility, and limitations

Conversion to VCD DAT normally reduces quality because the source is decoded and re-encoded as low-bitrate MPEG-1; changing the extension or remuxing cannot preserve an incompatible OGM video codec in a VCD stream. VCD resolution is also lower than most OGM sources, so downscaling is expected.

FFmpeg may omit OGM subtitles because standard VCD does not support arbitrary subtitle streams. To preserve them, burn the subtitles into the video before or during encoding, provided the required subtitle filter and source subtitle format are supported. Keep the original OGM because the DAT version is optimized for legacy compatibility rather than archival quality.