Convert Video Files Online for Free
Choose a video conversion by inspecting the source container, streams, codec settings, timing, and the receiving device.
- Add a file Choose or drop it here
- Pick the format Change it whenever needed
- Download the result After conversion completes
A Video Conversion Has Separate Container, Video, Audio, and Timing Decisions
A video filename is not a complete technical description. A container such as MP4, MOV, MKV, AVI, WebM, 3GP, or 3G2 can hold one or more timed tracks, but it does not by itself tell a player which decoder is needed. Each track has a codec, rate, channel layout or pixel characteristics, timestamps, and metadata. Start every conversion by inspecting the actual video and audio streams rather than selecting settings from the extension alone.
ISO Base Media File Format families illustrate why that separation matters. Their files describe each track as a sequence of timed samples; samples have decoding time and can have a composition-time offset. Movie and sample-table data describe the relationship and location of the media samples. A 3G2, 3GP, M4A, or MP4-looking file may therefore share structural ancestry but still contain incompatible codecs, time scales, brands, or target assumptions.
Define the receiver before choosing the output. A current browser, a messaging service, a television, an editing application, an archive policy, and an older mobile phone can have radically different requirements. The useful question is not simply “what extension should I use?” but “what exact video codec, audio codec, frame dimensions, rate, container, and metadata will this receiver accept?”
Remuxing Changes the Wrapper; Transcoding Creates New Compressed Media
A remux copies already-encoded audio and video packets into another container. It can be quick and avoid a new generation of compression, but it works only when the receiving container and player support those existing codecs and their configuration. Moving a stream to a different wrapper does not make a legacy video codec modern, make unsupported audio playable, or repair damaged timestamps. Verify compatibility before choosing a copy operation.
Transcoding decodes a source stream and encodes a target stream. That is required when codecs differ, when dimensions or frame rate must change, when a device accepts only a restricted profile, or when audio needs a different codec. Lossy video and audio transcoding discards information again. Keep the best original and avoid repeated exports through multiple lossy intermediates. If several delivery variants are needed, create them from the best available source rather than from another finished web delivery.
A hybrid job is common: copy a compatible video track while transcoding incompatible audio, or preserve audio while creating a GIF-style no-audio derivative. Record what was copied and what was re-encoded. That record explains why the result has a certain quality, duration, file size, or compatibility profile.
Frame Size, Pixel Format, Aspect Ratio, and Frame Rate Form the Video Contract
Width and height are only part of a video target. Pixel format and chroma subsampling influence whether an encoder and receiver can handle the output. Pixel aspect ratio and display aspect ratio can cause a visibly stretched or squeezed result even when the coded width and height look expected. Rotation metadata may be honored by one player and ignored by another, so bake or preserve orientation deliberately according to the target.
Frame rate requires similar care. A source may use a constant rate, variable frame durations, or timing based on sample tables. Converting to a new rate can duplicate or drop frames; doing so may affect motion cadence and audio synchronization. Do not create frames merely to make a rounded “frames per second” number look familiar. Check actual start, a known cut, a seek, and the end after conversion.
For an editing target, preserve an appropriate rate, resolution, and usable codec profile. For a mobile delivery target, dimensions and bitrate may need to respect hardware limits. For a GIF target, decide which frames to sample, how long each frame displays, how a palette is generated, and whether transparency applies. GIF is an animation image format and has no audio track.
Audio Tracks Need Codec, Language, Channel, and Synchronization Checks of Their Own
A video container can carry multiple audio tracks with different languages, channel layouts, descriptive roles, or codecs. Select the intended one explicitly. Audio copied into a new video file remains usable only if the new container and receiver support that audio codec. Audio transcoded to AAC, MP3, PCM, or another target must be tested for rate, channels, bitrate, delay, and end timing.
Do not silently downmix surround or stereo audio. A channel count is not a mix decision: downmixing can alter dialogue level, phase relationships, loudness, and spatial balance. If a target requires mono or stereo, document the mix policy and listen to it. Similarly, a video-only target such as GIF intentionally drops audio; keep a separate audio file or source reference if sound remains needed.
Audio/video sync is a timeline test, not only a duration test. Compare an identifiable sound and picture event near the beginning, middle, and end. If a drift appears, determine whether it comes from source timing, variable-frame-rate handling, resampling, frame-rate conversion, edit lists, or target playback. Padding one stream blindly can hide the symptom while leaving the cause unresolved.
3G2 and 3GP Show Why Similar Mobile Containers Are Not Interchangeable
3G2 is the 3GPP2 mobile multimedia format, historically associated with CDMA-based devices; 3GP is the 3GPP counterpart associated with GSM-oriented systems. Both are derived from the ISO Base Media File Format family and were designed around limited mobile storage and bandwidth, but their brands and permitted media can differ. A 3G2 can contain video and audio tracks and may encounter legacy voice codecs such as EVRC, QCELP, or SMV as well as more familiar MPEG-4 family media.
That history makes a “convert to 3G2” request device-specific. A new 3G2 file using a codec the original phone never supported can be structurally valid yet useless. Match exact phone documentation when the recipient is older hardware: video codec and profile, resolution, frame rate, audio codec, sample rate, channel count, bitrate, and sometimes brand. Treat 3G2-to-3GP as a potential remux only after stream inspection; otherwise transcode the incompatible track deliberately.
| Target question | What to inspect | Why it changes the result |
|---|---|---|
| Container | Actual wrapper, brands, track layout | Controls which streams can be packaged and recognized |
| Video codec | Codec, profile, pixel format, level | Determines decoder compatibility and transcode need |
| Timing | Sample durations, sync samples, edit behavior | Controls seeking, frame cadence, and sync |
| Geometry | Dimensions, pixel/display aspect, rotation | Prevents stretched or unexpectedly oriented video |
| Audio | Codec, language, channels, rate | Prevents silent or wrong-language output |
| Metadata | Title, date, chapters, location, cover data | Target schemas and applications differ |
Metadata, Chapters, and Location Data Must Be Deliberately Retained or Removed
Container metadata can include title, creation date, camera information, language, chapters, artwork, and location. A remux may retain some fields but a transcode or target container may not represent them in the same form. Inspect the result instead of assuming fields transferred because video plays. Privacy-sensitive location or device metadata should be considered before sharing; preservation-sensitive context should be exported or verified.
Chapters, subtitles, timed metadata, attachments, and alternate tracks are particularly easy to lose when making a simplified delivery. Decide whether the target requires them, whether it can store them, and whether a sidecar file is more appropriate. A conversion that is right for a short social upload can be wrong for a long-form archive or accessible presentation.
Approve a Video Conversion with Structural Inspection and Real-Receiver Playback
Before delivery, inspect the target container and every output stream independently: codec, profile, resolution, pixel format, frame rate or frame timing, display aspect, audio rate/channels, duration, bitrate mode, and metadata. Then open the file in the actual device, browser, service, or editor that prompted the conversion. Test beginning, seek points, difficult motion, an audio/video sync event, final boundary, subtitles or chapters where required, and target metadata display.
Can I change only a video extension?
No. A new extension does not change the container's boxes, codecs, or receiver compatibility.
When is remuxing enough?
Only when every existing stream and its timing/configuration are supported in the destination container and by the receiving player.
Why is the new file larger or smaller?
Codec choice, bitrate, frame rate, resolution, audio streams, and metadata all affect size; size alone does not prove quality.
Why is sound missing from a GIF?
GIF stores animation frames and palette data, not an audio track. Preserve sound separately when it is needed.
Are 3G2 and 3GP the same?
No. They are related ISO-BMFF-derived mobile formats with different 3GPP2 and 3GPP histories and potentially different device codec expectations.