From 488c85268b24c6b62ae5aa90c67adaa7f3c714c1 Mon Sep 17 00:00:00 2001
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Date: Tue, 17 Dec 2024 14:14:32 -0500
Subject: [PATCH] ffmpeg: Detect and fail on software decoder fallback

The goal of fluster is to test one specific implementation, allowing
software fallback hides possible integration issues.
---
 fluster/decoders/ffmpeg.py | 23 ++++++++++++++++-------
 fluster/utils.py           |  5 ++++-
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/fluster/decoders/ffmpeg.py b/fluster/decoders/ffmpeg.py
index 76823a6..6684997 100644
--- a/fluster/decoders/ffmpeg.py
+++ b/fluster/decoders/ffmpeg.py
@@ -23,7 +23,7 @@
 
 from fluster.codec import Codec, OutputFormat
 from fluster.decoder import Decoder, register_decoder
-from fluster.utils import file_checksum, run_command, run_command_with_output
+from fluster.utils import file_checksum, run_command_with_output
 
 
 @lru_cache(maxsize=128)
@@ -119,16 +119,25 @@ def decode(
         # MD5 muxer
         if self.use_md5_muxer and not keep_files:
             command.extend(["-f", "md5", "-"])
-            output = run_command_with_output(command, timeout=timeout, verbose=verbose)
+        # Output file
+        else:
+            command.extend(["-f", "rawvideo", output_filepath])
+
+        output = run_command_with_output(command, timeout=timeout, verbose=verbose, keep_stderr=True)
+
+        # Detect software fallback and turn this into an error
+        if self.hw_acceleration:
+            hw_error = re.search(r"Failed setup for format", output)
+            if hw_error:
+                raise Exception("Failed to use HW accelerator.")
+
+        if self.use_md5_muxer and not keep_files:
             md5sum = re.search(r"MD5=([0-9a-fA-F]+)\s*", output)
             if not md5sum:
                 raise Exception("No MD5 found in the program trace.")
             return md5sum.group(1).lower()
-
-        # Output file
-        command.extend(["-f", "rawvideo", output_filepath])
-        run_command(command, timeout=timeout, verbose=verbose)
-        return file_checksum(output_filepath)
+        else:
+            return file_checksum(output_filepath)
 
     @lru_cache(maxsize=128)
     def check(self, verbose: bool) -> bool:
diff --git a/fluster/utils.py b/fluster/utils.py
index cd50a07..63eefa5 100644
--- a/fluster/utils.py
+++ b/fluster/utils.py
@@ -88,9 +88,12 @@ def run_command_with_output(
     verbose: bool = False,
     check: bool = True,
     timeout: Optional[int] = None,
+    keep_stderr: bool = False,
 ) -> str:
     """Runs a command and returns std output trace"""
-    serr = subprocess.DEVNULL if not verbose else subprocess.STDOUT
+    serr = subprocess.DEVNULL
+    if verbose or keep_stderr:
+        serr = subprocess.STDOUT
     if verbose:
         print(f'\nRunning command "{" ".join(command)}"')