> On 28.05.2016 07:31, kl222 wrote: > > On 27.05.2016 13:49, Nicolas George wrote: > >> Can you explain your use case for this filter? > >> > >> I ask because I am very uncomfortable with filters that perform > >> direct output instead of producing frames for the rest of the graph. > >> They need to duplicate the encoding and muxing code, usually with > >> fewer options and features, and that duplicated code becomes itself a > >> maintenance burden in case of API changes and such. > >> > >> IMHO, a better solution would be some kind of "interactive select" > >> (or just an option of plain select) filter, and encode its output as > >> image2. > >> > > > > I want to implement to the snapshot function whenever push stream, and > > set the file name of snapshot picture. > > this function can snapshot pictures before, between or after the other > > filters. > > Because I want to change the file in filter, so duplicate the encoding > > and muxing code can not be avoided. > > OK, add it to "select" filter and a single filter patch. Chosen by you. see > annex. > > The way you added it to the select filter it still uses own muxing code and > doesn't allow to take full advantage of output format options. > > To give an idea what I had in mind when suggesting the select filter: The > following command uses current FFmpeg code to generate snapshot files of the > first two video > frames: > > ffmpeg -i input-file.avi -f image2 -q 5 -filter:v "select=lt(selected_n\,2)" > -y > snapshot-%03d.jpg > > Now if the select filter code would be improved to allow updating the > evaluated > expression at run-time, sending filter commands like > > expr lt(selected_n,2) // save two snapshot files expr lt(selected_n,3) // > add > another snapshot file expr lt(selected_n,4) // add another snapshot file > > could be used to trigger saving snapshot files on demand. >
I understand your usage scenario. But I am not specified snapshot file name on the command line. But it needs to be updated it is, another program specified file name. So, I think as a separate filter is better. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
