How to check converted files before sharing them

Write the acceptance criteria first

For an image, note the required dimensions, transparency and file-size limit. For audio, note the duration, channel count and whether the recipient needs a lossless file. For documents, identify a page with tables, unusual fonts or links. Those cases reveal mistakes that an easy first page can hide.

Keep the source unchanged. Convert into a separate output folder and use distinct names so the new file cannot be confused with the original.

Convert a representative sample

Recast provides batch queues and multi-step routing for supported format pairs. Its direct edition requires macOS 14 or later and supports Apple silicon and Intel. Check the exact input and output format in the app; a large format catalog does not mean every feature of every file can be preserved.

Start with one ordinary file and one difficult example. A multi-step route can be convenient, but intermediate formats may discard information. If the output cannot meet the acceptance criteria, use a different format or a tool specific to that task.

Inspect the output in the receiving app

• Images: inspect dimensions, sharp edges, color and transparency. JPEG does not preserve an alpha channel.
• Audio and video: compare duration, play the beginning and end, check all needed tracks and inspect synchronization.
• Documents: check page count, tables, fonts, searchable text and links.
• Data: compare row counts, headers, dates, leading zeros and totals. Read the CSV review guide for a detailed checklist.

A smaller file is not automatically a better result. Lossy formats trade fidelity for size; choose that trade deliberately.

Then run and review the batch

Run the remaining files only after the sample passes. Keep a list of failures and check a sample from each source type. Use the check sheet to record actual results. These are acceptance checks, not measured Recast speed or fidelity results.

Compare Mac converter options and local versus server-based conversion. Some browser converters process locally, so verify the data path instead of assuming that a web interface always uploads files.

Worked example: a transparent image for a slide

Suppose a presentation needs a logo with a transparent background. Keep the original, choose an output format that supports transparency and convert one copy. Place it on both a light and a dark slide: an unexpected rectangle or colored edge is easier to spot there. Check the pixel dimensions at the size the logo will actually appear.

If the destination requires JPEG, plan a deliberate background color because JPEG cannot retain transparency. Record that decision in the check sheet before processing the remaining logos. The goal is a usable result for the receiving app, not simply a smaller file.

When Recast fits

Recast is useful when you need repeatable local conversions across different file types. Available routes depend on macOS readers and writers and detected conversion tools. That does not imply every input-to-output combination is available. For one occasional conversion, first check whether your existing app can export the required format.

The Direct edition costs $10 once, requires macOS 14 or later on Intel or Apple silicon, and is signed and Apple notarized. Buy Recast — $10 once, or ask about your exact format pair before buying. Keep source files until you have checked the output.