Phone video to PC: which transfer keeps full quality
The first step of getting footage onto a computer sets the quality ceiling: the chat channel may have already compressed one generation, the file channel moves bytes untouched. The transfer choice matters more than any later transcode.
Three channels, two outcomes
Chat channel (sending via WeChat, QQ): compressed by default — WeChat transcodes videos to a lower bitrate on send. The app does offer an "original video" option, but you must tick it manually or the compressed version goes out. QQ behaves similarly; larger files survive better sent "as file". One line to remember: anything sent as a message may be compressed.
File channel (cable, AirDrop, LAN share, USB drive): bytes move untouched, quality lossless. Inside the Apple ecosystem AirDrop is easiest; across ecosystems use a cable or LAN. Cloud drives are file channels too, limited by upload bandwidth.
How to confirm nothing was compressed
The most direct evidence is size: matching byte counts before and after mean the file arrived untouched; a shrink means compression happened. A minute of iPhone 4K is hundreds of MB; the WeChat-compressed version is often a few MB — the difference is unmistakable. Compressed files have no recovery path: the lost detail is gone.
After confirming integrity, confirm compatibility: iPhone "High Efficiency" footage is HEVC-encoded MOV that Windows and some Android devices cannot open — convert to H.264 MP4 before it enters the edit pipeline.
First thing after the files land
Split by purpose: for publishing, compress locally to the target platform’s spec (bank headroom before the platform’s second compression); for archiving, keep high-bitrate copies and never re-transcode. Never shuttle footage back and forth through chat apps — every forward adds a generation of damage, while file channels stay on demand.
A habit worth keeping: create a read-only "originals" folder first and keep one untouched copy; do all processing on duplicates. The original is the quality ceiling — once touched, it never comes back.