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qcpostprod
qcpostprod
Participating Frequently
April 14, 2026
Open for Voting

Encoding a file using H.264 in MP4 format causes the audio and video to become out of sync.

When I use Media Encoder to transcode a video—for example, Apple ProRes 422 HQ with Linear PCM audio—After Effects and Premiere create a delay of about one frame between the audio and the video, which is very annoying. This problem only occurs when I set the output settings to MP4 H.264 with AAC audio.

 

As I need to deliver an MP4 H.264 file with AAC as the audio codec to my client, I have no choice but to use other video transcoding software. And in that case, I don’t have any issues with the audio and video being out of sync; the audio is exactly the same as in the source Apple ProRes file.

Is this a bug or have I configured the settings incorrectly?

I have attached my ME output preset along with a screenshot of the delay caused by the encoding .

 

Thanks.

      14 replies

      Dr.Rek
      Dr.Rek
      Known Participant
      October 8, 2026

      This issue seems to be over five years old, involving Adobe’s AAC audio encoding. Using uncompressed audio on a mp4 is a workaround. Encoding from a master file with other software like Compressor will be fine as Apple’s AAC codec compensates for the issue. Using a QuickTime h264 export out of Media Encoder or Premiere also works around this. https://www.reddit.com/r/AudioPost/comments/p56r8v/has_anyone_noticed_that_audio_is_delayed_by_about/

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        qcpostprod
        qcpostprodAuthor
        Participating Frequently
        October 19, 2026

        Thanks for your reply.

         

        Indeed I try different wrappers and there's no issue with QuickTime exports. But my client wants AAC audio wrapped in an MP4 and with a CBR bitrate. Unfortunately, Compressor does not allow CBR encoding for H.264.

        I really hope Adobe will fix Media Encoder by compensating this issue.

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        Dr.Rek
        Dr.Rek
        Known Participant
        October 19, 2026

        The track record of prioritizing new scaffolded on features rather than fixing ancient bugs that pros needed fixed a decade ago is a long one at Adobe.  Not sure without testing but you could try ffmpeg, ffworks is my favorite front end for that. 

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        EckiAME
        Community Manager
        EckiAMECommunity Manager
        Community Manager
        April 20, 2026

        What are your specs (OS, CPU, GPU, memory)? Can you provide a small sample for me to investigate? I can send you the instructions via private message in this forum.

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        qcpostprod
        qcpostprodAuthor
        Participating Frequently
        April 20, 2026

        Thanks for your feedback. Yes I can send you all the infos you need in PM.
         

        Here’s some infos :

         

        M4 14” MacBook Pro (2024) - 24 GB RAM - macOS Tahoe 26.4.1

        Adobe Media Encoder, After Effects, Premiere 26.2

         

        Also tested with other devices like Mac Studios on macOS 15 Sequoia, ME 25, and Windows configs from colleagues. Always the same problem.

         

        You’ll also find some new tests and sample files. My source is an Apple ProRes file which I use to create the social deliverables for my clients (they absolutely want MP4 H.264 with AAC audio)

         

        Thanks for your time and help

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        EckiAME
        Community Manager
        EckiAMECommunity Manager
        Community Manager
        April 20, 2026

        Would you be able to share a full project?

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