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March 2018

109 participants
102 discussions

Is there any approach to tell ffmpeg how to determine dts of fMP4 segment?
by toya3329 01 Mar '18

01 Mar '18

Hi, all! Does anyone known that when handling fMP4 segment dts timestampe, is there any approach to tell ffmpeg how to determine dts of fMP4 segment? (otherwise you have to rebuild all stuffs :<) The current choosing preference always make some fMP4 segments (with sidx earliest_presentation_time 0) to have the incorrect dts time stamp (0), although it was caused by an incorrect arliest_presentation_time. TIA -- Sent from: http://www.ffmpeg-archive.org/

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Why _COPYing_ a variable encoded audio (AAC) channel will produce a variably encoded one?
by Sophoklis Goumas 01 Mar '18

01 Mar '18

Hello. I have a .3gp file containing a video and an audio channel. I'm trying to get the audio channel in a separate m4a file but when I issue: ffmpeg -i foo.3gp -vn -c:a copy foo.m4a I get a constantly encoded AAC audio channel while the original was a variably encoded one. In more detail, from this: Format : AAC Format/Info : Advanced Audio Codec Format profile : LC Codec ID : mp4a-40-2 Bit rate mode : Variable Bit rate : 32.0 kb/s Maximum bit rate : 34.4 kb/s Channel(s) : 1 channel Channel positions : Front: C Sampling rate : 22.05 kHz Frame rate : 21.533 FPS (1024 SPF) Compression mode : Lossy Stream size : 82.4 MiB (60%) I end up with this: Format : AAC Format/Info : Advanced Audio Codec Format profile : LC Codec ID : mp4a-40-2 Bit rate mode : Constant Bit rate : 32.0 kb/s Channel(s) : 2 channels Channel(s)_Original : 1 channel Channel positions : Front: C Sampling rate : 22.05 kHz Frame rate : 21.533 FPS (1024 SPF) Compression mode : Lossy Stream size : 82.4 MiB (98%) Default : Yes Alternate group : 1 Thanks in advance, Sophoklis

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