How to run this ffmpeg command lines in hybrid？

[Selur]

I can't reproduce this here.
the original:

mediainfo.exe g:\Output\iId_2_aid_1_DELAY_-53ms_2023-02-08@15_48_34_7510_01.ac3 General Complete name : g:\Output\iId_2_aid_1_DELAY_-53ms_2023-02-08@15_48_34_7510_01.ac3 Format : AC-3 Format/Info : Audio Coding 3 Commercial name : Dolby Digital File size : 1.53 MiB Duration : 33 s 376 ms Overall bit rate mode : Constant Overall bit rate : 384 kb/s Audio Format : AC-3 Format/Info : Audio Coding 3 Commercial name : Dolby Digital Duration : 33 s 376 ms Bit rate mode : Constant Bit rate : 384 kb/s Channel(s) : 6 channels Channel layout : L R C LFE Ls Rs Sampling rate : 48.0 kHz Frame rate : 31.250 FPS (1536 SPF) Compression mode : Lossy Stream size : 1.53 MiB (100%) Service kind : Complete Main

converted to aac with 'tempo 0.80000000' gives:

mediainfo.exe g:\Output\iId_2_aid_1_ms_2023-02-08@15_48_34_7510_02.aac General Complete name : g:\Output\iId_2_aid_1_ms_2023-02-08@15_48_34_7510_02.aac Format : MPEG-4 Format profile : Base Media / Version 2 Codec ID : mp42 (M4A /mp42/isom) File size : 263 KiB Duration : 41 s 856 ms Overall bit rate mode : Variable Overall bit rate : 51.4 kb/s Encoded date : UTC 2023-02-08 14:48:56 Tagged date : UTC 2023-02-08 14:48:58 FileExtension_Invalid : braw mov mp4 m4v m4a m4b m4p m4r 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v Audio ID : 1 Format : AAC LC SBR Format/Info : Advanced Audio Codec Low Complexity with Spectral Band Replication Commercial name : HE-AAC Format settings : Explicit Codec ID : mp4a-40-2 Duration : 41 s 856 ms Bit rate mode : Variable Bit rate : 50.3 kb/s Maximum bit rate : 144 kb/s Channel(s) : 6 channels Channel layout : C L R Ls Rs LFE Sampling rate : 48.0 kHz Frame rate : 23.438 FPS (2048 SPF) Compression mode : Lossy Stream size : 257 KiB (98%) Writing library : Nero AAC codec 1.5.4.0 Encoding settings : -br 128000 Encoded date : UTC 2023-02-08 14:48:56 Tagged date : UTC 2023-02-08 14:48:58

Audio length did change as expected.

Is your input by any change vfr?

Cu Selur