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AV1

AV1 is Alchemist's most aggressive target codec. It produces the smallest files per unit of perceived quality, at the cost of slower encoding and narrower client compatibility than HEVC or H.264.

Alchemist treats AV1 as a first-class output: the planner knows AV1 has a better compression ceiling than HEVC (applies a 0.70× target multiplier when deciding whether a file is "already efficient enough"), and the encoder selection path prefers hardware AV1 when it's available.

Encoder paths​

Alchemist will use the first available AV1 encoder that passes its startup probe. In approximate preference order:

EncoderHardwareNotes
av1_nvencNVIDIA RTX 40 (Ada) seriesFast, GPU-accelerated; RTX 30 is AV1 decode-only
av1_qsvIntel Arc / Meteor Lake+Fast, power-efficient
av1_vaapiAMD RDNA 3+ (Linux) on compatible driver/FFmpegDriver/FFmpeg stack sensitive
av1_amfAMD RDNA 3+ (Windows)The AMD Windows path
libsvtav1 (CPU)Any CPUAlchemist's default CPU AV1 path — fastest of the CPU AV1 encoders
libaom-av1 (CPU)Any CPUHigher quality per bit, much slower

macOS has no AV1 hardware encoder. Apple's VideoToolbox exposes no AV1 encoder — Apple Silicon can decode AV1 (M3 and newer) but no Mac chip can encode it. On macOS, AV1 output always uses libsvtav1 (CPU).

Hardware support is detected at startup using a short FFmpeg probe. If you want to see what Alchemist found on your host, open Settings → Hardware → Probe Log — it records exactly which encoders passed and which failed, with the FFmpeg stderr captured for failures. See Hardware Acceleration for the selection policy.

Choosing AV1 as a target​

AV1 makes sense when storage savings matter more than compatibility and you're confident your playback devices handle AV1 decode without kicking the server back into live-transcode mode.

A short decision prompt:

  • Is your library mostly consumed on modern clients? (Recent Chromium browsers, 2023+ TVs, newer Apple devices, newer Android phones). AV1 is a reasonable target.
  • Do you have older clients in the mix? (2019-era TVs, Roku devices that lack AV1 decode, older browsers). HEVC is safer; AV1 will force Jellyfin / Plex to transcode back to something compatible, wiping out the savings.
  • Are you CPU-only? Encoding AV1 in software is slow even with SVT-AV1. That's fine for a library you're transcoding overnight in an off-peak window; less fine if you want results in hours.

For more on codec tradeoffs see Codecs.

When AV1 is not the right target​

AV1 isn't automatically the best answer. Pick HEVC or H.264 when:

  • Your clients don't reliably decode AV1 and you don't want live transcoding on the server.
  • You're running CPU-only on older hardware — SVT-AV1 is competitive, but HEVC on x265 is still noticeably faster.
  • Your library is already mostly HEVC 10-bit — Alchemist will skip those files by default (see already_target_codec). Re-targeting to AV1 and running again is possible, but you're trading real CPU/GPU time for marginal savings; watch the planner output before committing.

AV1 on Jellyfin​

See Alchemist for Jellyfin for the full context. The short version: AV1 gives the biggest space savings for libraries served to Jellyfin, but only if your clients direct-play it. When a client can't decode AV1, Jellyfin's own transcoder runs and the server does the work anyway. Pre-transcoding to a codec that every client in your house can direct-play is usually more useful than pre-transcoding to the smallest codec on paper.

Troubleshooting AV1​

AV1 encode requested but Alchemist fell back to CPU. Most likely the hardware AV1 probe failed — open Settings → Hardware → Probe Log. For NVIDIA, AV1 NVENC needs an RTX 40 (Ada) card; RTX 30 and older have NVENC but decode AV1 only. For Intel, AV1 encode needs Arc or a Meteor Lake / Core Ultra (or newer) iGPU. On macOS, AV1 always encodes on the CPU — there is no Mac AV1 hardware encoder. See CPU fallback despite GPU.

VAAPI AV1 errors on Linux. av1_vaapi is sensitive to driver and FFmpeg versions. If HEVC / H.264 VAAPI work but AV1 fails in the probe log, the driver stack is the usual cause. See the AMD hardware guide and Intel hardware guide.

AV1 file plays, but the UI shows a live transcode on the server. The client can't direct-play the resulting AV1 stream. Confirm with Jellyfin / Plex playback info and consider targeting HEVC for that library instead.

See also​