[fix] make position_id_per_seconds configurable for Qwen2OmniPlugin (#10281)

Co-authored-by: LincolnBurrows2017 <lincoln@example.com>

src/llamafactory/data/mm_plugin.py

@@ -1987,6 +1987,7 @@ class Qwen2OmniPlugin(Qwen2VLPlugin):
                             f"Each {VIDEO_PLACEHOLDER} must be followed by an {AUDIO_PLACEHOLDER} when using audio in video."
                         )
 
+                    position_id_per_seconds: int = getattr(processor, "position_id_per_seconds", 25)
                     audio_t_index = torch.arange(audio_lengths[num_audio_tokens])
                     video_t_index = (
                         torch.arange(video_grid_thw[num_video_tokens][0])
@@ -1998,9 +1999,9 @@ class Qwen2OmniPlugin(Qwen2VLPlugin):
                         )
                         .flatten()
                         * mm_inputs["video_second_per_grid"][num_video_tokens]
-                        * 25  # FIXME hardcode of position_id_per_seconds=25
+                        * position_id_per_seconds
                     ).long()
-                    t_ntoken_per_chunk = 50  # FIXME hardcode: [25 * 2]
+                    t_ntoken_per_chunk = position_id_per_seconds * 2
                     video_chunk_indices = processor.get_chunked_index(video_t_index, t_ntoken_per_chunk)
                     audio_chunk_indices = processor.get_chunked_index(audio_t_index, t_ntoken_per_chunk)
                     placeholder_string = ""