Hi, To record mp4 with libmp4v2, I found the standard audio format is AAC but FS does't support, so I tried added a mp3 encoder, hopefully it works. I have successfully record into mp4 but audio doesn't playback, videos looks fine. Anyone can help review the code and give some input is appreciated. http://fisheye.freeswitch.org/changelog/freeswitch.git?cs=084dac2540a15bfc00... Playback Errors in VLC looks like this: peg_audio decoder debug: emulated startcode (no startcode on following frame) [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode (no startcode on following frame) [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode (no startcode on following frame) [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode (no startcode on following frame) [0x105f10540] main audio output warning: buffer way too early (-126508), clearing queue [0x105f10540] main audio output warning: timing screwed, stopping resampling [0x10289faf0] mpeg_audio decoder debug: emulated startcode (no startcode on following frame) [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode [0x10289faf0] mpeg_audio decoder debug: emulated startcode (no startcode on following frame) I use mod_mp4v2(C) with libmp4v2 to record mp4 file, if also been interested I could share on github or check into the video-media-bug branch. But I really want to merge with mod_mp4 though which is C++ based. @Paulo, I also CC you this message as I haven't figure out how to write hint track you input is welcome. Thanks. -- Seven Du Sent with Sparrow (http://www.sparrowmailapp.com/?sig)