# What Is the Default Video Download Format in ReClip?

> ReClip downloads the highest quality video and audio merged into an MP4 container by default. Learn about ReClip's default video download format.

- Repository: [Avery Gan/reclip](https://github.com/averygan/reclip)
- Tags: faq
- Published: 2026-09-05

---

**ReClip defaults to downloading the highest‑quality video and audio streams merged into an MP4 container when no specific format is requested.**

The open‑source tool **ReClip** (available at `averygan/reclip`) automates media downloads through a REST API. When users submit a download request without specifying a format parameter, the application automatically applies its **default video download format** to ensure maximum quality and compatibility.

## How ReClip Determines the Default Video Format

ReClip intelligently selects media streams using **yt‑dlp** conventions when the client omits format details.

### The Default Format Logic in app.py

Inside [`app.py`](https://github.com/averygan/reclip/blob/main/app.py), the `start_download` function handles incoming API requests. When the `format` field is missing from the JSON payload, the server implicitly treats the request as a video download, defaulting the internal format identifier to `"video"`. This logic appears around **line 70** of the main application file.

The actual command construction occurs in the `run_download` function (lines 38‑44). If no specific `format_id` is provided, ReClip builds the yt‑dlp command with the following arguments:

```python
-f bestvideo+bestaudio/best --merge-output-format mp4

```

This instructs yt‑dlp to:
1. Select the **best available video stream**
2. Select the **best available audio stream**  
3. **Merge** both streams into an MP4 container using FFmpeg

## Technical Implementation Details

The default behavior leverages yt‑dlp's format selection syntax to guarantee the highest possible quality. The `bestvideo+bestaudio/best` fallback ensures that if separate video and audio streams are unavailable, yt‑dlp falls back to a combined best stream.

The `--merge-output-format mp4` flag forces the output container to MP4 regardless of the source codecs, ensuring broad device compatibility for the downloaded file.

## Using the ReClip API with Default Settings

To use the **default video download format in ReClip**, simply omit the `format` and `format_id` fields from your API request:

```bash
curl -X POST https://<host>/api/download \
     -H "Content-Type: application/json" \
     -d '{"url":"https://www.youtube.com/watch?v=example"}'

```

The server responds with a `job_id`. Upon completion, the downloaded file will be an MP4 containing the highest‑quality video and audio streams available for that URL.

### Overriding the Default

To bypass the default and request a specific quality (for example, format ID `137`), include the optional parameters:

```bash
curl -X POST https://<host>/api/download \
     -H "Content-Type: application/json" \
     -d '{
           "url":"https://www.youtube.com/watch?v=example",
           "format":"video",
           "format_id":"137"
         }'

```

When `format_id` is present, ReClip skips the `bestvideo+bestaudio` logic and requests that specific stream directly.

## Summary

- **ReClip defaults to `bestvideo+bestaudio`** merged into an MP4 file when downloading video content without explicit format instructions.
- The default logic resides in [`app.py`](https://github.com/averygan/reclip/blob/main/app.py), specifically within the `start_download` (line 70) and `run_download` (lines 38‑44) functions.
- The implementation utilizes **yt‑dlp** with the arguments `-f bestvideo+bestaudio/best --merge-output-format mp4`.
- Users can override the default by supplying a specific `format_id` in the API request body.

## Frequently Asked Questions

### What container format does ReClip use by default?

ReClip outputs **MP4** as the default container format. The `--merge-output-format mp4` argument in the yt‑dlp command ensures that even when source streams use different codecs, the final merged file is packaged as a universally compatible MP4.

### Can I override the default video download format in ReClip?

Yes. You can override the default by including a `format_id` parameter in your API request. When provided, ReClip passes this specific ID to yt‑dlp instead of using the `bestvideo+bestaudio` selector, allowing you to download exact resolutions or codecs as needed.

### What happens if the best video and audio streams are incompatible?

The `/best` fallback in the format selector (`-f bestvideo+bestaudio/best`) ensures that if yt‑dlp cannot merge the separate streams due to codec incompatibility, it automatically falls back to selecting the single best combined stream available, maintaining download reliability.

### Where in the codebase is the default format configured?

The default format is configured in **[`app.py`](https://github.com/averygan/reclip/blob/main/app.py)**. The logic that defaults requests to video format appears in the `start_download` function around line 70, while the command construction using `bestvideo+bestaudio` and the MP4 merge flag occurs in the `run_download` function between lines 38 and 44.