Rev.ai is a leading speech-to-text API. You send it an audio or video file (or a URL pointing to one), and it returns a transcript. It's accurate, supports 36+ languages, and handles speaker diarization, custom vocabulary, and confidence scores.
ChangeThisFile doesn't do transcription. It converts files between formats. Where these tools meet: Rev.ai has specific format requirements for optimal accuracy, and real-world recordings often come in formats that need preparation — a MOV from an iPhone, an MKV from a screen recorder, a FLAC from an audio workstation, or a video where you only need the audio track.
This comparison covers how to use ChangeThisFile as part of a Rev.ai transcription workflow, and where each tool fits.
Quick verdict
Need to transcribe audio or video to text? Rev.ai. ChangeThisFile doesn't do transcription — that's not the job.
Have an audio or video file in a format Rev.ai doesn't accept, or want to extract audio before sending? ChangeThisFile first, then Rev.ai.
Need to extract just the audio from a large video file before transcription? ChangeThisFile — extract MP3 or WAV from MP4/MOV/MKV, then send the audio file to Rev.ai. Smaller upload, faster processing.
Want to test the workflow? ChangeThisFile's free tier is 1,000 conversions/month with no card. Rev.ai has a free trial with 5 hours of transcription.
Pricing comparison
Competitor pricing below is as of April 2026 - check the vendor's current pricing page before deciding.
| Plan | ChangeThisFile | Rev.ai |
|---|---|---|
| Free tier | 1,000 conversions/month (no card) | 5 hours transcription free (trial) |
| Entry paid | $29/mo — 10,000 conversions | ~$0.02–0.05/min (pay-as-you-go) |
| $99/mo equiv. | $99 Startup — 50,000 conversions | ~1,980–4,950 transcription minutes |
| High volume | $499 Scale / $1,999 Growth | Volume pricing available |
| Billing model | Per conversion (file format change) | Per audio minute transcribed |
These are complementary costs, not competing ones. Rev.ai bills for transcription time; ChangeThisFile bills for format conversion. In a combined workflow, you'd pay both — but ChangeThisFile's conversion cost per file is typically small (one conversion credit), and transcription is usually the dominant cost.
Extracting audio before transcription can also reduce Rev.ai costs: sending a 500MB MOV to Rev.ai vs a 5MB MP3 of the same audio uses the same transcription minutes (billed on audio duration, not file size) but can reduce upload time and processing overhead.
Format coverage and preparation
Rev.ai accepts common audio and video formats: MP3, WAV, FLAC, OGG, AAC, M4A, MP4, MOV, and others. However, performance and accuracy can vary by format, codec, and quality level. The general guidance for best results: send high-quality mono or stereo WAV or MP3 at 16kHz+.
ChangeThisFile conversion routes useful for Rev.ai prep:
| Source File | Convert To | Why |
|---|---|---|
| MOV (iPhone video) | MP3 or WAV | Extract audio only — smaller upload, no video data |
| MKV (screen recording) | MP3 or WAV | Extract audio for transcription |
| MP4 (meeting recording) | MP3 | Audio-only upload — 90%+ smaller file |
| FLAC (high-quality audio) | MP3 or WAV | If FLAC upload causes issues |
| OGG (browser recording) | MP3 or WAV | More universally accepted format |
| WMV (Windows video) | MP4 or MP3 | Compatibility with Rev.ai ingest |
| AAC (podcast audio) | MP3 | Standard transcription input format |
Combined workflow: ChangeThisFile + Rev.ai
A typical two-step workflow for transcribing video recordings:
Step 1: Extract audio with ChangeThisFile
# Extract MP3 audio from an MP4 meeting recording
curl -X POST https://changethisfile.com/v1/convert \
-H "Authorization: Bearer ctf_sk_your_key" \
-F "file=@meeting.mp4" \
-F "target=mp3" \
--output meeting.mp3
Step 2: Transcribe with Rev.ai
# Submit to Rev.ai for transcription
curl -X POST https://api.rev.ai/speechtotext/v1/jobs \
-H "Authorization: Bearer $REVAI_KEY" \
-F "media=@meeting.mp3" \
-F "options={\"language\":\"en\"}"This approach reduces upload size (video files are often 10–50x larger than the extracted audio), ensures format compatibility, and keeps costs minimal on both APIs.
In Python or Node, both calls can be chained in a simple wrapper function: convert → upload → poll for transcript → return text.
API simplicity
ChangeThisFile has one endpoint. No SDK required. Source format is auto-detected from the filename. You only specify the target format.
curl -X POST https://changethisfile.com/v1/convert \
-H "Authorization: Bearer ctf_sk_your_key" \
-F "file=@podcast.ogg" \
-F "target=mp3" \
--output podcast.mp3
Rev.ai has a well-documented REST API with SDKs for Python, Node, Go, and Java. The job-based async API (submit → poll or webhook → fetch transcript) is clean and developer-friendly. Their machine learning models support speaker diarization, custom vocabulary, and confidence scoring.
Both APIs are developer-friendly. They serve different steps in the same pipeline — ChangeThisFile prepares the file, Rev.ai processes it.
When to use each
| Task | Tool |
|---|---|
| Convert speech to text | Rev.ai |
| Speaker identification in transcripts | Rev.ai |
| Custom vocabulary for domain-specific terms | Rev.ai |
| 36+ language transcription support | Rev.ai |
| Extract audio from a video before transcription | ChangeThisFile |
| Convert audio to MP3/WAV for Rev.ai compatibility | ChangeThisFile |
| Normalize MKV/WMV/OGG before upload | ChangeThisFile |
| Reduce upload size before transcription | ChangeThisFile (extract audio first) |
Rev.ai and ChangeThisFile solve adjacent problems and work well together. Use ChangeThisFile to extract and normalize audio from your source files, then send clean MP3 or WAV files to Rev.ai for transcription. The prep step is one API call, free for up to 1,000 files/month. Get a free API key — no card, no client library to install.