On 9/11/16 12:30 PM, Steve wrote: > Steve wrote >> Steve wrote >>> I'm using ffmpeg audio decoding to create a gapless audio loop. I call >>> av_seek_frame (with AVSEEK_FLAG_BACKWARD) to seek to my desired time, and >>> call avcode_flush_buffers after. It seems the first decoded frame in the >>> audio stream after the seek contains a few samples of silence or near >>> silence, thus making the loop not gapless. >>> >>> If I skip an arbitrary amount of samples, the gap disappears. I've tried >>> bypassing any swr_convert resampling with same results and also using the >>> deprecated avcodec_decode_audio4 instead of the >>> avcodec_send_packet/av_read_frame scheme. >>> >>> Is there a way to know how many samples I need to skip so I exactly hit >>> the >>> actual audio data, or prevent ffmpeg from having these filler samples in >>> AVFrame->data after the seek? >> I should also mention I know that the av_seek_frame won't seek to the >> exact time requested, it's on the packet boundary. I can account for the >> number of samples I need to skip to get to the exact time, but when the >> number of samples is low (or I try without skipping these samples), the >> problem of the silence samples is evident. >> >> This is using the mp3 decoder. > Incidentally this is ONLY happening with mp3 decoder (the most popular > format!). The other decoders like aac, wma, flac don't have this silence > gap. I guess it's some sort of bug. > > I also experience behavior like this with WMA Pro. I am forced to perform my own rollback on seeking.
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