To generate this patch, we can follow these reasoning steps:

Step 1. Root Cause Analysis:

1. Identify the resource allocation:
   - Line 14 allocates a filter context using `avfilter_graph_alloc_filter()`.
   - The allocated filter context is stored in `*filt_ctx`.

2. Analyze the error path:
   - Lines 25-35 handle the initialization of the filter.
   - If initialization fails (ret < 0), the function returns with an error.

3. Identify the vulnerability:
   - In the error case, the function returns without freeing the allocated filter context.
   - This leads to a memory leak (CWE-401) as the allocated memory is not released.

Step 2. Fixing Strategy:

1. Resource management principle:
   - Resources should be freed when they are no longer needed, especially in error paths.

2. Identify the correct deallocation function:
   - For AVFilterContext, the appropriate deallocation function is `avfilter_free()`.

3. Determine the placement of the fix:
   - The deallocation should occur just before returning from the error path.
   - This ensures the resource is freed if initialization fails.

4. Implement the fix:
   - Add a call to `avfilter_free(*filt_ctx)` before returning in the error case.

Therefore, the patch should be:

```
<         av_log(log_ctx, AV_LOG_ERROR, "\n");
<         return ret;
---
>         av_log(log_ctx, AV_LOG_ERROR, "\n");
>         avfilter_free(*filt_ctx);
>         return ret;
```

This patch ensures that the allocated filter context is properly freed if initialization fails, preventing the memory leak.