Free online FLV to H263 converter

What the FLV format is

FLV, or Flash Video, is a container created for Adobe Flash Player and commonly used by older video-hosting sites, browser-based recorders, screen-capture tools, and Flash authoring software. An FLV file can contain different video codecs, including Sorenson Spark, VP6, and H.264, plus MP3 or AAC audio. The .flv extension identifies the container, not the codec inside it.

What the H.263 format is

H.263 is an older video-compression standard designed for low-bitrate video conferencing and telecommunication systems. It is found in legacy videophones, early mobile-video services, some 3GPP files, and hardware or software that supports only baseline H.263. Its low data rate can suit limited-bandwidth systems, but it generally produces lower quality than modern H.264 or H.265 at the same bitrate.

H.263 does not normally define audio storage or a general-purpose file container. A raw H.263 elementary stream contains video only; audio must be preserved separately or placed with the encoded video in a compatible container such as 3GP.

How to convert FLV to H.263

Using FFmpeg for a raw H.263 stream

FFmpeg is the most direct desktop method. Install a current FFmpeg build, open a terminal in the folder containing the source file, and run:

ffmpeg -i input.flv -c:v h263 -b:v 256k -an output.h263

This decodes the FLV, re-encodes the video with the H.263 encoder at 256 kbit/s, removes audio with -an, and writes a raw .h263 stream. Replace the filenames and bitrate as required.

To scale the video for an older H.263 device, add a compatible size such as QCIF:

ffmpeg -i input.flv -vf scale=176:144 -c:v h263 -b:v 128k -an output.h263

To create a 3GP file with H.263 video and retained or converted audio, use:

ffmpeg -i input.flv -c:v h263 -b:v 256k -c:a aac -b:a ความassistant彩在线 64k -f 3gp output.3gp

Use the 3GP option only when the receiving device accepts 3GP rather than a raw .h263 file. Some older devices require AMR audio instead of AAC; that depends on the device specification and the FFmpeg build.

Using the online converter

You can convert the file for free on 101convert.com without installing software. Upload the FLV, select H.263 or the requested H.263-compatible output, start the conversion, and download the resulting file. Check whether the service produces a raw H.263 stream or a container such as 3GP before transferring it to the target application.

Quality, compatibility, and limitations

Conversion is usually lossy because the source video is decoded and encoded again. The original FLV codec, frame size, frame rate, and bitrate determine how much detail can be preserved; increasing the H.263 bitrate cannot restore detail already lost in the source.

H.263 implementations are less uniform than modern codecs. Confirm the required frame dimensions, frame rate, bitrate, packetization, file extension, and audio format before converting. Raw .h263 output may not open in a normal media player because it has no timestamps, metadata, or audio track.

If the FLV already contains H.263 video, FFmpeg may be able to copy the video without re-encoding, but a raw-stream conversion can still require remuxing:

ffmpeg -i input.flv -c:v copy -an output.h263

Use this only when the input codec is actually H.263 and the resulting stream is accepted by the destination; otherwise use -c:v h263 to perform a real conversion.