Clarify fixed GOP canvas count

app.py

@@ -1584,7 +1584,6 @@ with gr.Blocks(**_BLOCK_KW) as demo:
                 gop = gr.Radio(
                     [
                         ("GOP = 4 — fixed 4-frame groups",                "4"),
-                        ("GOP = 5 — fixed 5-frame groups",                "5"),
                         ("GOP = 8 — fixed 8-frame groups",                "8"),
                         ("GOP = 16 — fixed 16-frame groups",              "16"),
                         ("Codec-stream: adaptive groups by saliency energy", "dynamic"),
@@ -1595,8 +1594,10 @@ with gr.Blocks(**_BLOCK_KW) as demo:
                          "produces exactly one GOP canvas: the group's first "
                          "frame stays whole as the I-frame, and each later "
                          "frame gets its own P section below it. So GOP=4 "
-                         "becomes I P P P, GOP=5 becomes I P P P P. With 32 "
-                         "sampled frames and GOP=8, this yields 4 canvases. "
+                         "means each group is I P P P. For fixed GOP=N, the "
+                         "number of packed canvases is ceil(sampled_frames / N). "
+                         "Example: 32 sampled frames with GOP=4 gives 8 "
+                         "canvases; 32 sampled frames with GOP=8 gives 4. "
                          "Codec-stream mode adaptively groups by saliency "
                          "energy, targeting roughly 8-64 sampled frames per group.",
                 )
@@ -1674,7 +1675,8 @@ with gr.Blocks(**_BLOCK_KW) as demo:
                             "<b>I/P structure</b>: the group's first frame is "
                             "the <b>I-frame</b> kept whole on top, and each "
                             "later frame gets its own packed <b>P-frame</b> "
-                            "section below in time order.</small>"
+                            "section below in time order. Fixed GOP=N means "
+                            "<b>one canvas per N sampled frames</b>.</small>"
                         )
                         canvas_out = gr.Gallery(
                             label="", show_label=False,