A 3GP file was originally created by the 3rd Generation Partnership Project as a simple mobile video format for early 3G handsets that struggled with tiny storage, weak processors, and short battery life, so it used a lightweight MP4-style structure that favored compact size and dependable playback, bundling timing info with video formats like H.263 or baseline H.264 and audio formats like AMR—an extremely low-bitrate speech codec—causing thin voices and loss of background sound today.
One of the biggest challenges with 3GP files now is silent playback, which nearly always traces back to AMR being unsupported rather than the file being defective; modern players and browsers avoid AMR because it complicates licensing or doesn’t fit typical media pipelines, and editors—favoring AAC or PCM—often refuse AMR entirely, making it look like the audio was removed even though it was intentionally ignored.
The 3G2 format, which stems from CDMA networks rather than GSM, fares significantly worse on modern systems because its audio codecs—EVRC, QCELP, or SMV—are almost never supported today, so tools must decode and re-encode this telecom audio into AAC to restore sound, revealing that the original file relied on outdated network-specific voice compression.
Instead of being structurally opposite like AVI and MKV, 3GP and 3G2 are sibling formats based on the same ISO Base Media File Format as MP4, meaning their boxes and timing structures look nearly identical, and the practical difference comes from ftyp identifiers—3gp5 or 3g2a—that many software tools treat as optional.
To put it briefly, 3GP and 3G2 belonged to an outdated era of mobile technology where compatibility meant running on early phones, not today’s systems, so silent audio or playback failures arise from legacy codecs, and the straightforward remedy is converting the audio into a supported format while keeping the video as is.
