Ffmpeg Convert All Files In Folder Windows

FFmpeg: Batch Converting All Files in a Windows Folder

FFmpeg is a powerful command-line tool capable of handling a vast array of multimedia tasks. One common need is batch processing—converting multiple files within a folder simultaneously, saving considerable time and effort. This comprehensive guide details how to efficiently convert all files in a Windows folder using FFmpeg, covering various scenarios and offering advanced techniques for customization.

Understanding the Fundamentals: FFmpeg and Batch Conversion

Before diving into the specifics, let's clarify the core concepts. FFmpeg's strength lies in its flexibility; it can handle virtually any video and audio format. Batch conversion leverages this power by automating the process, applying the same conversion parameters to multiple files. This eliminates the need to manually process each file individually.

The key to batch conversion is the use of the command prompt (cmd.exe) and understanding how to combine FFmpeg commands with Windows batch scripting.

The Basic Batch Conversion Command

The simplest way to convert all files in a folder involves using a for loop within a batch script (.bat file). This loop iterates through each file, applying the FFmpeg conversion command.

Here's a basic example:

@echo off
for %%a in (*.mp4) do ffmpeg -i "%%a" -c:v libx265 -crf 28 -c:a aac -b:a 128k "%%~na.mkv"
pause

Explanation:

• @echo off: Prevents commands from being displayed in the console.
• for %%a in (*.mp4) do: This loop iterates through all files ending with .mp4 in the current directory. %%a represents the current file.
• ffmpeg -i "%%a": This invokes FFmpeg, specifying the input file (%%a).
• -c:v libx265 -crf 28: This encodes the video using the x265 encoder (high efficiency H.265) at a constant rate factor (CRF) of 28 (lower values mean higher quality, larger files). Adjust the CRF value based on your desired balance between quality and file size.
• -c:a aac -b:a 128k: This encodes the audio using the AAC codec at 128kbps. You can adjust the bitrate as needed.
• "%%~na.mkv": This constructs the output filename. %%~na extracts the filename without the extension, appending .mkv to create the output file.

How to Use:

1. Save the code: Save the above code as a .bat file (e.g., convert.bat).
2. Place the file: Put the .bat file in the folder containing the .mp4 files you want to convert.
3. Run the script: Double-click the .bat file to execute it.

Important Note: This script converts only .mp4 files to .mkv. Modify (*.mp4) to target different file extensions (e.g., *.avi, *.mov).

Handling Different File Types and Output Folders

The previous example is limited to a single input and output type and location. Let's expand upon it to handle multiple input types and specify a separate output folder.

@echo off
mkdir "output"
for %%a in (*.mp4 *.avi *.mov) do ffmpeg -i "%%a" -c:v libx264 -crf 23 -c:a copy "output\%%~na.mp4"
pause

Explanation:

• mkdir "output": Creates an "output" folder if it doesn't exist. This keeps the converted files organized.
• for %%a in (*.mp4 *.avi *.mov) do: This loop processes .mp4, .avi, and .mov files.
• "output\%%~na.mp4": The output files are now placed in the "output" folder.

Advanced Techniques and Error Handling

Let's incorporate more robust error handling and logging.

@echo off
echo Starting conversion process... > conversion_log.txt
mkdir "output" 2>nul
for %%a in (*.mp4 *.avi *.mov) do (
  echo Processing: %%a >> conversion_log.txt
  ffmpeg -i "%%a" -c:v libx264 -crf 23 -c:a copy "output\%%~na.mp4" 2>&1 | findstr /i "error" >> conversion_log.txt
  echo Finished processing %%a >> conversion_log.txt
)
echo Conversion complete. Check conversion_log.txt for details.
pause

Explanation:

• echo ... > conversion_log.txt: Creates a log file to record the process.
• mkdir "output" 2>nul: Silently creates the output folder (errors are suppressed).
• 2>&1 | findstr /i "error": Redirects standard error output to the log file, filtering for lines containing "error" (case-insensitive). This helps identify any problems during conversion.

Customizing the Conversion Parameters

The conversion parameters are crucial for controlling the output quality and file size. Experiment with these to achieve your desired results:

• -c:v (Video Codec): Choose the codec based on your needs:
  • libx264: H.264 encoding (widely compatible).
  • libx265: H.265 encoding (better compression, requires more processing power).
  • libvpx-vp9: VP9 encoding (good quality and compression).
• -crf (Constant Rate Factor): A value between 18 and 28. Lower values mean higher quality and larger file sizes. 23 is a good starting point.
• -c:a (Audio Codec):
  • aac: Advanced Audio Coding (common and good quality).
  • copy: Copies the audio stream without re-encoding (fastest but may not be compatible with all output formats).
• -b:a (Audio Bitrate): Specified in kbps (kilobits per second). Higher bitrates result in better audio quality but larger file sizes.

Scaling and Resizing Videos

You can resize videos during conversion using the -vf (video filter) option. For example, to resize to 720p:

for %%a in (*.mp4) do ffmpeg -i "%%a" -vf scale=1280:720 -c:v libx264 -crf 23 -c:a copy "%%~na_720p.mp4"

This adds the scale=1280:720 filter to resize the video to 1280x720 pixels.

Subtitles and Metadata

FFmpeg allows you to include subtitles and modify metadata during conversion. Consult the FFmpeg documentation for detailed instructions on these advanced features.

Conclusion

This guide provides a solid foundation for batch converting files in a Windows folder using FFmpeg. By understanding the basics of batch scripting and utilizing the flexible options offered by FFmpeg, you can automate your video and audio conversion tasks, significantly improving workflow efficiency. Remember to adjust the parameters to suit your specific needs and always consult the FFmpeg documentation for the most up-to-date information and advanced features. By mastering these techniques, you'll unlock the full potential of FFmpeg for your multimedia projects. Happy converting!