WebM video seeking not smooth as MP4 video

[Duc Dim]

Hi, I have a FLV file convert to WebM to get transparent background, but when seek the WebM video I realize it's not smooth as MP4 video, have to wait a bit after seeking(I test on localhost), not sure I'm missing something, I use Shutter Encoder to conver FLV to WebM with configuration below(this software use ffmpeg to do the task)

[James Zern]

Hi,

On Wed, Jan 18, 2023 at 6:43 PM Duc Dim <dimavn...@gmail.com> wrote:

Hi, I have a FLV file convert to WebM to get transparent background, but when seek the WebM video I realize it's not smooth as MP4 video, have to wait a bit after seeking(I test on localhost), not sure I'm missing something, I use Shutter Encoder to conver FLV to WebM with configuration below(this software use ffmpeg to do the task)

Do you see the same behavior if you disable alpha?

 

[Duc Dim]

Hi sorry for very late reply, if I disable the alpha channel(the background will be blank) the seeking is smoothly, is there any thing that I can do to improve this? Thank you

[Duc Dim]

Hi sorry for late reply, yes if I disable alpha, the video seek smoothly, how do I improve seeking when enable alpha chanel?

On Thursday, January 19, 2023 at 11:35:08 AM UTC+8 James Zern wrote:

[James Zern]

On Fri, May 12, 2023 at 12:33 AM Duc Dim <dimavn...@gmail.com> wrote:

Hi sorry for very late reply, if I disable the alpha channel(the background will be blank) the seeking is smoothly, is there any thing that I can do to improve this? Thank you

Try the 'Set GOP to' option in your encoder to a smaller value. The delay is most likely due to the fact that Alpha and Video are encoded separately and their keyframe selection may differ; the ffmpeg wrapper doesn't force a keyframe on the alpha side if it sees one on the video side.

If there are any options indicating delay or lag, set those to 0 too. This corresponds to VP8/VP9 alternate reference frames which may cause issues when seeking the two streams.