We re-package or re-encode your MP4 into the FLV container. When the codec matches, we copy streams (fast, lossless); when it does not, we re-encode with H.264 / H.265 / VP9 at a high default quality.
Is converting MP4 to FLV lossy?
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If the codec inside MP4 is compatible with FLV, the conversion is a remux (no quality loss). If we need to re-encode, the default CRF setting is visually lossless for typical viewing distances.
Yes when FLV supports them (MP4, MKV, MOV). All audio tracks, languages, and embedded subtitles are kept. For single-track containers (3GP, FLV), only the default track survives.
How big can my MP4 file be?
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Free accounts have a size limit that varies by file type; PRO accounts allow much larger files. For very large MP4 files we recommend the PRO plan or pre-trimming with our video-trim tool.
What codec is used inside the FLV output?
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We pick the best-supported codec for the FLV container — H.264 for MP4 / MOV / FLV, VP9 for WebM, AV1 when targeting modern web, H.265 when FLV supports it. You can override in the options panel.
Will my converted FLV play on TV, phone, and browser?
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Yes. Our default profile targets universal playback — H.264 + AAC inside FLV works on every major platform, browser, and smart TV from the last decade.
Is the MP4 to FLV converter free?
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Yes, within the free size limit. PRO unlocks larger files, GPU-accelerated transcoding, and 4K output.
Does PDF.to support 4K and HDR MP4 files?
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Yes. 4K is preserved by default; downscale via the options panel if needed. HDR is preserved when FLV supports it (MKV, MP4 with HEVC) or tonemapped to SDR when targeting older formats.
