Convert DVR to FLAC — Free Online Tool
Extract and preserve the audio track from a DVR recording as a lossless FLAC file, decoding the AAC audio stream and re-encoding it with FLAC's lossless compression so every detail of the original captured audio is retained without any further quality degradation.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your DVR file here
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
DVR files typically carry an AAC audio stream alongside an H.264 (libx264) video stream, stored in a proprietary container used by digital video recorders for broadcast capture or surveillance footage. Because FLAC is a pure audio format with no video container support, the video stream is completely discarded during this conversion — only the audio track is processed. The AAC audio is fully decoded to uncompressed PCM, then re-encoded using FLAC's lossless compression algorithm at compression level 5, which is the balanced default between encoding speed and file size. Crucially, lossless means the decoded PCM waveform is bit-for-bit identical to what you would get from fully decoding the output FLAC file — no audio information is lost in the FLAC encoding step itself. The quality ceiling of the output is therefore determined entirely by the quality of the original AAC audio in the DVR recording, not by the FLAC encoding process.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which is running here as FFmpeg.wasm compiled to WebAssembly and executing entirely inside your browser — no data is sent to any server. |
-i input.dvr
|
Specifies the input DVR file. FFmpeg will probe and demux the proprietary DVR container to locate the audio and video streams inside, typically finding an H.264 video track and an AAC audio track. |
-c:a flac
|
Sets the audio codec to FLAC for the output. This tells FFmpeg to decode the source AAC audio to raw PCM and then re-encode it using the lossless FLAC codec, which will appear in the output .flac file. No video codec is specified because FLAC cannot contain video. |
-compression_level 5
|
Sets FLAC's internal compression effort to level 5, the default midpoint on a scale of 0 (fastest, largest file) to 8 (slowest, smallest file). This controls only encode speed and output file size — all levels produce bit-for-bit identical audio when decoded. |
output.flac
|
Defines the output filename and format. The .flac extension tells FFmpeg to write a standard FLAC audio file containing the losslessly compressed audio extracted from the DVR recording, with no video data included. |
Common Use Cases
- Extracting a clean audio archive from surveillance DVR footage for use as evidence, where bit-accurate audio preservation is required for legal or compliance purposes.
- Pulling the audio from a DVR-captured broadcast television recording — such as a live event or news segment — to archive it in a lossless format for long-term storage before the DVR footage is overwritten.
- Recovering the spoken audio from a security camera recording to create a transcript, using FLAC as the input to a high-accuracy speech-to-text service that performs better with lossless source files.
- Separating the audio commentary or ambient sound from a DVR recording of a sports event to use as a standalone lossless reference track in a video production workflow.
- Converting DVR audio to FLAC as an intermediate, lossless step before further processing — such as noise reduction or loudness normalization — to avoid accumulating lossy re-encoding artifacts across multiple passes.
- Archiving audio from aging or failing DVR hardware whose proprietary format may become unreadable in the future, preserving the audio content in the widely supported, open FLAC format.
Frequently Asked Questions
No — FLAC is lossless, meaning it perfectly preserves whatever audio quality exists in the source, but it cannot recover quality that was already lost when the DVR originally encoded the audio as AAC. The AAC codec in DVR recordings is lossy, so any compression artifacts from that original encoding are baked into the audio waveform. The FLAC output will be a lossless snapshot of the decoded AAC audio, which is as good as that audio can ever be, but it will not sound better than the original DVR file.
This is expected and counterintuitive. The DVR file stores audio as compressed AAC, which is a highly efficient lossy codec that can represent audio at very small bitrates (commonly 128k). FLAC is lossless, so while it does compress audio, it must retain all the decoded waveform data — the output file size is driven by the audio's sample rate, bit depth, and duration, not by a target bitrate. A one-hour recording at 44.1 kHz / 16-bit stereo will produce a FLAC file of roughly 1.5–2 GB regardless of how small the source AAC stream was.
The video stream is entirely dropped. FLAC is an audio-only format and has no capacity to store video data, so FFmpeg extracts only the audio track from the DVR file and discards the H.264 video stream. If you need to keep the video, you would need to convert to a container format like MKV or MP4 instead. No separate video output file is created by this command.
Metadata preservation from DVR files is limited and format-dependent. DVR is a proprietary container and typically stores minimal or non-standard metadata compared to formats like MP4. FFmpeg will attempt to map any recognized metadata tags to FLAC's Vorbis comment tag structure, but fields like recording timestamp, channel name, or device-specific tags embedded by the DVR hardware are likely to be lost or unmapped. FLAC natively supports standard tags such as TITLE, ARTIST, and DATE, which you can add manually after conversion.
Change the value after -compression_level in the command. The valid range is 0 through 8, where 0 is the fastest encoding with the largest file size and 8 produces the smallest file but takes significantly longer to encode. Critically, every compression level produces bit-identical audio output — the level only affects encoding speed and output file size, never audio quality. For most archiving workflows, the default of 5 is a sensible choice, but if you are batch-processing large numbers of long DVR recordings, lowering to 1 or 2 will dramatically speed up the process with only a modest file size penalty.
The single-file command shown here processes one file at a time, but you can adapt it for batch processing in a shell script. On Linux or macOS, use: for f in *.dvr; do ffmpeg -i "$f" -c:a flac -compression_level 5 "${f%.dvr}.flac"; done. On Windows Command Prompt, use: for %f in (*.dvr) do ffmpeg -i "%f" -c:a flac -compression_level 5 "%~nf.flac". Each DVR file in the directory will be converted to a corresponding FLAC file. This is especially useful for bulk-archiving footage from a DVR system that stores recordings as individual files per event or time segment.
Technical Notes
DVR is not a single standardized format — it is a proprietary container term used across multiple manufacturers (Hikvision, Dahua, and others), which means FFmpeg's ability to parse the input depends on whether the specific DVR variant conforms closely enough to a recognized container structure. Most modern DVR systems internally use MPEG-4 or H.264 in a container closely related to MP4 or AVI, making them generally compatible with FFmpeg's demuxers. The audio codec is most commonly AAC at 128k, though some systems use MP3 (libmp3lame). In both cases, the audio must be fully decoded and then re-encoded to FLAC — there is no lossless passthrough possible from a lossy source. The -compression_level 5 parameter controls only the DEFLATE-like compression ratio applied to the lossless FLAC frames and has zero effect on audio fidelity. FLAC does not support multiple audio tracks, chapters, or subtitles, so if the DVR recording contained any secondary audio streams, only the first (default) audio track will be encoded. The output FLAC file is fully compatible with all major music players, DAWs, and audio tools including VLC, foobar2000, Audacity, and any platform supporting the open FLAC standard.