[Libav-user] dts/pts generated by aac encoder less than zero

[Hendrik Leppkes]

On Fri, Oct 9, 2015 at 7:53 AM, qw <applemax82 at 163.com> wrote:
> Hi,
>
> I use avcodec_encode_audio2() to call aac encoder to compress audio.
> AVFrame::pts is set to 0 for 1st frame, 1 for 2nd frame, 2 for 3rd frame,
> and so on. But I find pts and dts are negtive values in 1st two output
> packets, and 3rd packet's pts/dts is 0. Why pts and dts are less than 0 in
> 1st two output packets?

Encoders will produce negative timestamps when they have a delay.
Otherwise they would cause A/V desync, since the audio is delayed.