Upload your MP4 video. PDF.to pulls the audio track out, encodes it to M4A, and gives you a M4A-only download. The video stream is discarded.
Will the audio in the M4A match the original MP4 quality?
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If the source audio is already in a codec compatible with M4A, we stream-copy without re-encoding — bit-identical to the original. Otherwise we re-encode at 192 kbps by default for near-transparent quality.
What bitrate is the M4A output?
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192 kbps by default. The options panel exposes 96, 128, 192, 256, and 320 kbps — pick higher for music, lower for voice.
Can I extract only part of the MP4 as M4A?
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Yes. Use the trim controls on the upload preview to set start and end times before extracting, and only that range becomes M4A.
Does the converter handle MP4 files with multiple audio tracks?
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Yes. If your MP4 has several language or commentary tracks, you can pick which one(s) to extract as M4A in the options panel.
Will the M4A output have the same sample rate as the source?
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Yes by default. We do not resample unless you explicitly request it. 48 kHz is preserved from movie sources, 44.1 kHz from music sources.
Is the MP4 to M4A extraction free?
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Yes for files under 100 MB. PRO supports larger MP4 files (5 GB) and parallel batch extraction.
Does PDF.to read or store my MP4 content?
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No. The MP4 video and the M4A audio output are deleted within an hour. Conversion runs in an isolated worker.
Can I batch-extract audio from multiple MP4 files?
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Yes — drop a folder of MP4 videos and you will get a ZIP of M4A files back, one per source video.
Will the M4A preserve tags and metadata?
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Title, artist, and album tags are populated from the MP4 container metadata when available. You can edit them after extraction with our audio-tag tool.
Does the converter work on streaming video URLs?
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No — PDF.to converts files you upload, not third-party stream URLs. Download the MP4 legally first, then upload it for M4A extraction.
Why is the M4A file much smaller than the MP4 video?
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Because the video stream (typically 90%+ of file size) is discarded. Only the audio track ends up in the M4A, which is why it can drop from gigabytes to a few megabytes.