OTB is a bitmap format for mobile devices, used for operator logos and graphics sent via SMS.
HRZ is an image format for slow-scan television (SSTV), used by amateur radio operators to transmit images over radio.
FreeFileConvert uses tuned encoding for OTB to HRZ conversions, preserving clarity while trimming file size. Finished audio streams instantly across phones, tablets, desktops, and modern browsers without extra tweaks.
Upload OTB files from desktop, tablet, or cloud storage, queue multiple jobs, and let the converter finish autonomously. Return whenever convenient to download synchronized HRZ results on any device you rely on.
Process up to 5 files sized 1000 MB per batch without splitting queues manually. Mixed-format uploads convert together, producing consistent HRZ audio with dependable progress tracking.
OTB images are small monochrome bitmaps optimized for mobile transmission.
HRZ files contain low-resolution images optimized for transmission over narrow-bandwidth radio channels.
Upload your image file in the OTB format from your device, Dropbox, or Google Drive.
Select HRZ as the output format and click Convert. Adjust optional settings if needed.
Download the converted image file. Each file stays available for up to 5 downloads.