[FFmpeg-trac] #2839(avformat:new): Wasted work in av_new_program() and avpriv_new_chapter()

[FFmpeg]

#2839: Wasted work in av_new_program() and avpriv_new_chapter()
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             Reporter:  pchang9      |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avformat
              Version:  unspecified  |               Resolution:
             Keywords:  performance  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Changes (by michael):

 * component:  undetermined => avformat


Comment:

 using a ts stream the old loop in av_new_program() executes in 50 cpu
 cycles, the new after the patch in 77 cycles.
 in 30 seconds the code gets about 1000 times executed in my test file
 which makes this loop take 0.00008% of the execution time.
 Thus this code does not appear to be performance relevant and your change
 makes it slower. At least for the testcase i used.
 also please always test performance improvment suggestions and include the
 test results in the ticket.
 Do you have a testcase for these 2 patches that shows a improvment ?

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2839#comment:1>
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