AVCHD to AVCHD Converter

AVCHD to AVCHD: Why Would You Convert a File to Itself?

Because this is not a rename and it is not a passthrough. The video is decoded and a completely new H.264 stream is encoded, the audio is decoded and re-encoded as AC-3, and the result is re-muxed. Nothing is copied through untouched. That costs you a generation of quality, so it is only worth doing when you want to change something inside the file while keeping the .avchd name that an archive index, an ingest folder or an editing project has been told to expect.

The honest reasons are these four:

• Shrink it. Camcorders record at roughly 17 to 24 Mbps for 1080-line footage, which is far more than most finished material needs.
• Cut it. The Trim control encodes only the section you ask for, so a two-minute excerpt from a forty-minute recording stays a two-minute file.
• Normalise a folder. Queue a batch of mismatched recordings and give them all one bitrate and one frame size.
• Fix the frame size. Bring an oversized or anamorphic recording to a raster your project actually wants.

If none of those is your goal, do not run this conversion — the original file is better than any copy of it this page can make. And if your real aim is a file that plays and edits everywhere, AVCHD to MP4 gives you the same H.264 video in a container every phone, browser and editor understands.

What the .avchd File Actually Is

This matters more than anything else on the page. AVCHD as a format is a directory structure — a BDMV or AVCHD folder with a STREAM subdirectory of .mts or .m2ts files, plus index and playlist files — not a single file with an .avchd extension. What this converter can write is the media, not the folder tree.

Two consequences. First, rename the download if anything refuses to open it: change the extension to .ts and the bytes match what the name claims, because plain 188-byte framing is exactly what a .ts file is. Second, the codec pair is genuinely AVCHD-legal — the specification calls for H.264 video with Dolby AC-3 or linear PCM audio, and AC-3 is what this page writes, which is not true of our .mts and .m2ts targets. If you need the file to sit inside a real camcorder folder structure, you will have to place it there yourself; no single-file conversion can build one.

How to Convert AVCHD to AVCHD

1. Upload Your AVCHD File: Drag the file onto the page or click "+ Add Files" to browse. Several recordings can be queued and they all take the same settings, which is the point when you are normalising a batch.
2. Pick a File Compression mode: The page opens on Quality Preset at Very High (Recommended). Specific file size, Constant Bitrate, Variable Bitrate, Constant Quality and Constraint Quality are the alternatives. On H.264 the Constant Quality slider is a genuine CRF running 16 to 51 and opening at 23, where lower means better quality and a larger file.
3. Set Video resolution and Trim: Video resolution opens on Keep original, with Resolution Percentage, Preset Resolutions, Width, Height and Width x Height available. Trim switches from Unchanged to Time Range with a Start time and a Duration — the single most effective way to make a camcorder file smaller.
4. Convert and Download: Click Convert and save the file. Files are uploaded over an encrypted connection, re-encoded on our servers and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public.

What the Quality Preset Really Sets

Because H.264 supports CRF, the preset maps to a specific quality value rather than to a bitrate, and the value is nudged by frame size — larger frames tolerate a slightly higher CRF because dense pixels hide artefacts, so the number moves by up to two either way from these 1080-line figures:

To put numbers on what that means, we ran a six-second 1920 x 1080 clip at 25 fps, written at a camcorder-like 17 Mbps with an AC-3 track — 12,600,512 bytes to begin with. At CRF 18, the preselected Very High setting, it came back at 6,615,908 bytes. At CRF 23 it was 4,344,304, and at CRF 28 it was 2,170,272. Those ratios depend heavily on how much detail and motion your footage has, but the direction is reliable: the default preset roughly halves a camcorder file, and dropping to Medium roughly halves it again.

If you need to hit a specific number rather than a specific quality, Specific file size computes the bitrate from your target and the clip duration, and Constant Bitrate sets a flat rate. Both are more predictable than guessing at presets when there is a hard limit to meet.

Frequently Asked Questions

Can I re-wrap the file without re-encoding it?

No. There is no stream-copy path on this page — the H.264 video and the AC-3 audio are both decoded and encoded again on every run, so each pass is a fresh generation of lossy compression. If nothing about the size, bitrate, resolution or length needs to change, keep the original file. If you only want a shorter clip, Trim AVCHD is aimed at that job, and Video Cutter accepts .avchd directly.

Why does my media player not recognise the file?

Because .avchd is not an extension players register. The bytes inside are an ordinary MPEG transport stream — we checked the output and found the sync byte 0x47 at offset 0 with the next packet 188 bytes later, exactly the layout of a .ts file. Rename the download to .ts and it opens in VLC, in FFmpeg-based players and in most editors. Nothing about the file changes; you are just giving it a name software already knows.

Is the output a real AVCHD disc or card structure?

No, and this is the most common misunderstanding about the format. A camcorder writes AVCHD as a folder tree — BDMV or AVCHD directories containing a STREAM subdirectory of numbered .mts files plus index and playlist files — and that structure is what authoring software looks for. A single file cannot be a structure. What this page produces is the media stream on its own, with an AVCHD-legal codec pair inside it. Placing it into a folder tree is a separate job.

Why can I not choose a different codec?

Because AVCHD does not permit one. The specification calls for H.264 video with Dolby AC-3 or linear PCM audio, so the Video Codec list has exactly one entry and the Audio Codec list has exactly one. That constraint is also a small advantage: our .mts and .m2ts targets default to AAC, which is not AVCHD-legal audio, whereas this page's AC-3 is.

My footage looks squashed after I resized it. What happened?

You almost certainly have anamorphic footage. Plenty of AVCHD camcorders record 1440 x 1080 with non-square pixels that a player stretches to 16:9 on display. On Keep original that pixel-aspect flag is preserved and the picture looks right. Any resize, however, flattens the pixel aspect to square — so a 1440 x 1080 anamorphic clip scaled down comes out looking narrow. The fix is to set an explicit Width x Height in the proportions you actually want to see, for example 1920 x 1080, rather than a percentage or a height-only preset.

Will this fix the interlacing in my 1080i footage?

No. There is no deinterlacing step anywhere in this pipeline, so the combing in interlaced camcorder material is decoded as recorded and encoded straight back into the output. Reducing the resolution makes it look worse, because the interleaved fields get blended together. If your footage is interlaced and the result matters, deinterlace it in a desktop editor before uploading.

How do I get the file under a specific size?

Use Specific file size rather than the Quality Preset. Enter your target and the pipeline derives a bitrate from it and the clip duration, which is the only mode that aims at a number instead of at a quality level. Trimming first helps more than any compression setting on long recordings — halving the duration halves the file exactly, with no quality cost at all. Compress AVCHD is the dedicated page if size reduction is the whole job.

Is the Constant Quality number the same CRF I use in my editor?

Close enough to be useful. It is a genuine x264 CRF value and the slider runs 16 to 51, opening at 23, with lower meaning better quality and a bigger file. The one thing to note is the floor: the slider does not go below 16, so the very top of the CRF scale is not reachable here. If you want maximum quality, use the Highest preset instead, which maps to CRF 17 on a 1080-line frame.

Should I be converting to MP4 instead?

For most purposes, yes. The video inside an AVCHD file is already H.264 — the same codec an MP4 carries — so moving to MP4 costs you the same single re-encode this page does while producing a file that phones, browsers, TVs and every editor open without argument. Use AVCHD to MP4 unless something specifically requires the transport-stream layout, in which case AVCHD to MTS writes the same 188-byte framing under a name camcorder software recognises.

What happens to my footage after the conversion?

It is uploaded over an encrypted connection, re-encoded on our servers, and both the upload and the output are deleted automatically after a few hours. Nothing is shared or made public, and there is no sign-up or watermark. Camcorder files are big and the transfer is what you will spend time waiting on, so trimming before you upload — or converting in modest batches — gets you through a shoot far faster than one long queue.