"Bypass re-encode when possible" is a Deliver page checkbox that copies video straight out of your source file instead of encoding it again — but only when the output matches the source, and only for clips you have not touched. The second half is where most people lose it, and there is a third catch that almost nobody mentions: for the codecs most editors actually work in, Blackmagic's own table says passthrough is not available at all.
Here is the control in the DaVinci Resolve 21 Reference Manual's own words (p.4202):
"Bypass re-encode when possible: Turning this checkbox on makes it possible to do a direct copy of the video essence of video items in the Timeline, directly from the source media to the file being output, when the selected Format, Codec, and Type matches the source. This also preserves Alpha channel data for compatible formats."
Three things have to line up — Format, Codec and Type — before anything gets copied. Type is its own dropdown, separate from Codec: the manual's ProRes Master preset description sets "the Codec set to Apple ProRes, and the Type set to Apple ProRes 422 HQ." So matching the container and the codec family is not enough on its own.
What quietly switches it off
The manual is unusually specific about what forces a re-encode, and the list is longer than "did you grade it":
"Bypass re-encode eliminates the need to re-encode video media, preserves quality, and speeds up the output process dramatically, but it only works for clips in the Timeline to which no additional effects have been added. Doing any grading, adding a Resolve FX plugin, adding any overlapping effects or compositing to clips in the Timeline, resizing or stabilizing clips or altering the output sizing of the Timeline, and adding Fusion effects will all necessitate re-encoding the entire clip in order to process these effects. Transitions will require processing but only for the duration of each transition."
Two details in there are worth pulling out:
- It is per clip, and it takes the whole clip. The manual says these actions "necessitate re-encoding the entire clip" — not just the affected frames.
- Altering the output sizing of the Timeline counts. You do not have to touch a single clip. Changing the Timeline's output sizing is listed alongside grading and Fusion.
- Transitions are the one partial case. Processing is required "but only for the duration of each transition."
The three workflows Blackmagic puts forward are all round trips rather than fresh edits. The first is quoted below; the other two on that page are replacing a few shots in an already-rendered program (Resolve direct-copies the previously rendered media and re-encodes only the new clips), and dropping a new audio mix onto a previously rendered Video+Audio clip, where the video component is not re-encoded.
"Fast output of simple edits: You've edited a simple cuts-only promo using footage cut from a previously rendered program using QuickTime ProResHQ 422 media, and you're exporting to the exact same format. You can output all of the media very quickly using Bypass re‑encode when possible."
The lookup the manual sends you on
Right below that setting, the manual tells you where to check compatibility:
"TIP: For a list of which video formats are compatible with Bypass Re-encode on macOS, Windows, and Linux, as well as which formats are compatible with Alpha channels, see the "Supported Codec List" at the DaVinci Resolve Support page located at: https://www.blackmagicdesign.com/support/family/davinci-resolve-and-fusion."
Follow that and you hit a versioning trap. Blackmagic's document server currently hosts three files in this series, and the one named for the newest version is not the newest document:
| File | Pages | What the document says about itself |
|---|---|---|
DaVinci_Resolve_19_Supported_Codec_List.pdf | 15 | Cover reads "August 2024" |
DaVinci_Resolve_20_Supported_Codec_List.pdf | 14 | Cover reads "July 2025" |
DaVinci_Resolve_21_Supported_Codec_List.pdf | 11 | Every page footer reads "DaVinci Resolve 15 BETA Supported Formats and Codecs" |
If you download by version number — the obvious move when you are running Resolve 21 — you get the 11-page file, and its columns are Format | File Ex. | Codec | Decode | Encode only. There is no Bypass Re-encode column and no Alpha column in it, so the table the TIP describes is not there.
The columns exist in the July 2025 file, which is the one named for version 20. Its header row reads, verbatim, Format | File Ex. | Alpha Exports | Codec Passthrough(1) | Decode | Encode, split into separate chapters for mac OS, Windows and Rocky Linux 8.6 (CUDA). "Codec Passthrough" is the column name you are looking for — the phrase "Bypass Re-encode" does not appear as a column header. Its footnote spells out that the two are the same idea:
"(1) Indicates if codec renders can be sped up by reusing the original source video essence if there are no effects or color changes to the clip. Relevant only for formats that can be read and rendered by DaVinci Resolve."
Which formats actually have Codec Passthrough
Straight out of that column in the July 2025 list:
| Format | Codec Passthrough |
|---|---|
| Apple ProRes (mov, mkv) | mov |
| Apple ProRes (mxf Op1A / Op-Atom) | – |
| DNxHD | Yes |
| DNxHR | Yes |
| GoPro CineForm (avi / mov) | Yes |
| Grass Valley (avi / mov) | Yes |
| Uncompressed (avi / mov / mxf) | Yes |
| JPEG2000 video | for IMFs |
| JPEG2000 still (j2c) | Yes |
| Sony (mov / mxf) | for XAVC |
| H.264, H.265, MV-HEVC, AV1, VP9 | – |
Read the ProRes row carefully. The cell says mov, not "Yes", and the MXF-wrapped ProRes row says –. So "ProRes passes through" is too loose: the mov-wrapped one does, the MXF-wrapped one does not.
Why an untouched H.264 cut still gets re-encoded
That last row is the answer to a question people ask constantly. H.264, H.265, MV-HEVC, AV1 and VP9 show – in the Codec Passthrough column on every platform and in every container listed. Trim a phone clip, apply nothing, tick the checkbox, export — and the picture is still encoded again, because the codec has no passthrough entry to begin with.
That matters because those are exactly the codecs consumer footage arrives in. If your export of an ungraded H.264 clip came out softer or larger than the original, a re-encode is the ordinary explanation, and Bypass re-encode is not a lever you can pull against it in Resolve.
When all you need is a smaller file out of an H.264 source — not a colour-managed master — a round trip through an editor is the wrong tool. Re-compressing the file directly avoids the timeline entirely:
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
That runs inside your browser tab: the file is read from disk, re-encoded locally and handed back, never uploaded. The same engine with the knobs exposed sits on the compressor page, and every Clapr tool is listed in one place. For how quality-based encoding settings behave generally, HandBrake's RF value explained covers the trade-off from the encoder side.
The Alpha half of the same checkbox
The manual's sentence "This also preserves Alpha channel data for compatible formats" points at the other column in that July 2025 table, Alpha Exports. A few entries that are easy to get wrong:
- H.265 on macOS: Alpha Exports is "Yes" in mov and mkv, and
–in mp4. Same codec, same machine — the container decides. - Apple ProRes: "4444", i.e. the Alpha capability is tied to that variant rather than to ProRes generally.
- DNxHR: "Yes (except LB)" — the LB variant is carved out by name.
Blackmagic's own note at the end of that document applies to all of it: "Specifications format and codec support subject to change without notice." Check the current file before you plan a delivery around any one cell. More export walkthroughs live in the guides hub.
FAQ
Where is "Bypass re-encode when possible" in DaVinci Resolve? It is a checkbox in the Deliver page render settings, documented on p.4202 of the DaVinci Resolve 21 Reference Manual.
Why does Bypass re-encode do nothing for my H.264 timeline?
Because H.264 has no Codec Passthrough entry. In the July 2025 Supported Formats and Codecs list, H.264, H.265, MV-HEVC, AV1 and VP9 all show – in that column, on every platform and container listed.
Does a colour-corrected clip still pass through? No. The manual lists "any grading" among the actions that "necessitate re-encoding the entire clip," together with Resolve FX plugins, overlapping effects or compositing, resizing, stabilizing, altering the Timeline's output sizing, and Fusion effects.
Do transitions break it for the whole timeline? No. The manual's wording is that "Transitions will require processing but only for the duration of each transition."
Which Supported Codec List PDF should I be reading?
The one whose cover reads "July 2025" — despite being named for version 20, it is the file that carries the Alpha Exports and Codec Passthrough(1) columns. The file named for version 21 has a page footer reading "DaVinci Resolve 15 BETA Supported Formats and Codecs" and neither column. For anything you plan to rely on, check the official documentation on Blackmagic's support page.
Quotations from the DaVinci Resolve 21 Reference Manual (p.4202) and Blackmagic's Supported Formats and Codecs PDF dated July 2025, checked 16 September 2026. Blackmagic states that format and codec support is subject to change without notice — verify against the current documents.
