H261 File

What are H261 files and how to open them

Are you having problems opening a H261 file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your H261 files.

What is a H261 file?

A .H261 file is a Raw H.261 Video file.

A raw H.261 video file is a video clip compressed with the H.261 standard without any extra container structure around it. It stores only the compressed video bitstream itself, typically produced by tools or hardware that encode directly in H.261; no audio or metadata is embedded. Files like this are useful for conversion, research or streaming over protocols that expect pure video data.

H.261 was developed by ITU-T in the late 1980s for video conferencing and telephony over ISDN lines, where data rates are multiples of 64 kbps. It defines how video is divided into frames (also called pictures), groups of blocks (GOBs), and macroblocks. During encoding, prediction, discrete cosine transform, quantization, and Huffman coding are used to compress luminance and chrominance information. Raw H.261 files contain only the output of that compression process.

When transmitted over networks, H.261 bitstreams are often packetised for RTP (Real-time Transport Protocol). In this use, each packet carries a header with fields like SBIT, EBIT (defining padding bits at start/end), I (intra-frame flag), V (motion vector usage), GOB number, macroblock address predictor, quantizer value, and motion vector data. These fields precede blocks of encoded video data.

Technical identifiers: tools like FFmpeg recognize raw H.261 files using codec ID "AV_CODEC_ID_H261" and label them "raw H.261" when no container is present.

How to open H261 files

We have identified one H261 opener that is compatible with this specific type of H261 file.

Programs that open Raw H.261 Video files

Last updated: August 6, 2026

Various apps that use files with this extension

These apps are known to open certain types of H261 files. Remember, different programs may use H261 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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