cli: clearer errors for unsupported extensions and failed audio decode

[aryanrahar]

Add early extension check (stdin “-” still supported).
On decode failure, print a concise hint with a one-line ffmpeg command.
Keep supported set consistent with usage text (flac, mp3, ogg, wav).
Print timings only if at least one file was processed successfully.
Improves UX for cases like #3375 without changing core behavior.

Manual tests:
samples/jfk.wav → transcribes + timings
bad.m4a → “unsupported extension … (flac, mp3, ogg, wav) + ffmpeg hint”, no timings
bad.mp3 (corrupt) → “failed to decode … (detected .mp3) + ffmpeg hint”, no timings
stdin (-f -) still works

[aryanrahar]

????????????

[danbev]

@aryanrahar Can you take a look at the commit and update it, as it is a little difficult to review at the moment. It looks like some formatting has been applied perhaps.

[aryanrahar]

@aryanrahar Can you take a look at the commit and update it, as it is a little difficult to review at the moment. It looks like some formatting has been applied perhaps.
Thanks for the heads-up — I’ve removed the accidental formatting and force-pushed a minimal diff.
Changes only:
Add #include and
Early extension check (skips -/stdin) — supported: flac, mp3, ogg, wav
Clearer decode-failed message with a one-line ffmpeg hint
Print timings only after a successful run (processed_any guard)
When you have a moment, could you please take another look? I’m eager to keep working on this project and can turn around any feedback quickly.

[danbev]

Perhaps the extension validation could be extracted into a separate function to not "interfer" with the normal code path. For example, something like this:

diff --git a/examples/cli/cli.cpp b/examples/cli/cli.cpp
index a87dab1c..7a7ba113 100644
--- a/examples/cli/cli.cpp
+++ b/examples/cli/cli.cpp
@@ -1,5 +1,5 @@
 #include <filesystem>
-#include <algorithm>   
+#include <algorithm>
 #include "common.h"
 #include "common-whisper.h"
 
@@ -128,6 +128,38 @@ static char * requires_value_error(const std::string & arg) {
     exit(0);
 }
 
+static bool validate_audio_extension(const std::string & fname_inp) {
+    if (fname_inp == "-") {
+        return true; // stdin is always valid
+    }
+
+    std::string ext;
+    try {
+        ext = std::filesystem::path(fname_inp).extension().string();
+        std::transform(ext.begin(), ext.end(), ext.begin(),
+                       [](unsigned char c){ return std::tolower(c); });
+    } catch (...) {
+        // ignore; let the decoder try
+        return true;
+    }
+
+    auto ext_supported = [](const std::string &e) {
+        // keep in sync with usage: "supported audio formats: flac, mp3, ogg, wav"
+        return e == ".wav" || e == ".mp3" || e == ".flac" || e == ".ogg";
+    };
+
+    if (!ext.empty() && !ext_supported(ext)) {
+        fprintf(stderr,
+            "error: unsupported audio extension '%s' for '%s'.\n"
+            "supported: flac, mp3, ogg, wav.\n"
+            "hint: convert with ffmpeg, e.g.:\n"
+            "      ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
+            ext.c_str(), fname_inp.c_str(), fname_inp.c_str());
+        return false;
+    }
+    return true;
+}
+
 static bool whisper_params_parse(int argc, char ** argv, whisper_params & params) {
     for (int i = 1; i < argc; i++) {
         std::string arg = argv[i];
@@ -1108,43 +1140,20 @@ int main(int argc, char ** argv) {
         std::vector<float> pcmf32;               // mono-channel F32 PCM
         std::vector<std::vector<float>> pcmf32s; // stereo-channel F32 PCM
 
-        std::string ext;
-if (fname_inp != "-") {
-    try {
-        ext = std::filesystem::path(fname_inp).extension().string();
-        std::transform(ext.begin(), ext.end(), ext.begin(),
-                       [](unsigned char c){ return std::tolower(c); });
-    } catch (...) {
-        // ignore; let the decoder try
-    }
-}
-
-auto ext_supported = [](const std::string &e) {
-    // keep in sync with usage: "supported audio formats: flac, mp3, ogg, wav"
-    return e == ".wav" || e == ".mp3" || e == ".flac" || e == ".ogg";
-};
-
-if (fname_inp != "-" && !ext.empty() && !ext_supported(ext)) {
-    fprintf(stderr,
-        "error: unsupported audio extension '%s' for '%s'.\n"
-        "supported: flac, mp3, ogg, wav.\n"
-        "hint: convert with ffmpeg, e.g.:\n"
-        "      ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
-        ext.c_str(), fname_inp.c_str(), fname_inp.c_str());
-    continue;
-}
+        if (!validate_audio_extension(fname_inp)) {
+            continue;
+        }
 
-// Try to read/decode the audio. If it fails, give an actionable hint.
-if (!::read_audio_data(fname_inp, pcmf32, pcmf32s, params.diarize)) {
-    std::string det = ext.empty() ? "" : (" (detected extension: " + ext + ")");
-    fprintf(stderr,
-        "error: failed to decode audio from '%s'%s.\n"
-        "Make sure the file is not corrupted and has one of: flac, mp3, ogg, wav.\n"
-        "If you still hit this, convert to a standard WAV with:\n"
-        "  ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
-        fname_inp.c_str(), det.c_str(), fname_inp.c_str());
-    continue;
-}
+        // Try to read/decode the audio. If it fails, give an actionable hint.
+        if (!::read_audio_data(fname_inp, pcmf32, pcmf32s, params.diarize)) {
+            fprintf(stderr,
+                "error: failed to decode audio from '%s'.\n"
+                "Make sure the file is not corrupted and has one of: flac, mp3, ogg, wav.\n"
+                "If you still hit this, convert to a standard WAV with:\n"
+                "  ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
+                fname_inp.c_str(), fname_inp.c_str());
+            continue;
+        }
 
         if (!whisper_is_multilingual(ctx)) {
             if (params.language != "en" || params.translate) {

[aryanrahar]

Perhaps the extension validation could be extracted into a separate function to not "interfer" with the normal code path. For example, something like this:

diff --git a/examples/cli/cli.cpp b/examples/cli/cli.cpp
index a87dab1c..7a7ba113 100644
--- a/examples/cli/cli.cpp
+++ b/examples/cli/cli.cpp
@@ -1,5 +1,5 @@
 #include <filesystem>
-#include <algorithm>   
+#include <algorithm>
 #include "common.h"
 #include "common-whisper.h"
 
@@ -128,6 +128,38 @@ static char * requires_value_error(const std::string & arg) {
     exit(0);
 }
 
+static bool validate_audio_extension(const std::string & fname_inp) {
+    if (fname_inp == "-") {
+        return true; // stdin is always valid
+    }
+
+    std::string ext;
+    try {
+        ext = std::filesystem::path(fname_inp).extension().string();
+        std::transform(ext.begin(), ext.end(), ext.begin(),
+                       [](unsigned char c){ return std::tolower(c); });
+    } catch (...) {
+        // ignore; let the decoder try
+        return true;
+    }
+
+    auto ext_supported = [](const std::string &e) {
+        // keep in sync with usage: "supported audio formats: flac, mp3, ogg, wav"
+        return e == ".wav" || e == ".mp3" || e == ".flac" || e == ".ogg";
+    };
+
+    if (!ext.empty() && !ext_supported(ext)) {
+        fprintf(stderr,
+            "error: unsupported audio extension '%s' for '%s'.\n"
+            "supported: flac, mp3, ogg, wav.\n"
+            "hint: convert with ffmpeg, e.g.:\n"
+            "      ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
+            ext.c_str(), fname_inp.c_str(), fname_inp.c_str());
+        return false;
+    }
+    return true;
+}
+
 static bool whisper_params_parse(int argc, char ** argv, whisper_params & params) {
     for (int i = 1; i < argc; i++) {
         std::string arg = argv[i];
@@ -1108,43 +1140,20 @@ int main(int argc, char ** argv) {
         std::vector<float> pcmf32;               // mono-channel F32 PCM
         std::vector<std::vector<float>> pcmf32s; // stereo-channel F32 PCM
 
-        std::string ext;
-if (fname_inp != "-") {
-    try {
-        ext = std::filesystem::path(fname_inp).extension().string();
-        std::transform(ext.begin(), ext.end(), ext.begin(),
-                       [](unsigned char c){ return std::tolower(c); });
-    } catch (...) {
-        // ignore; let the decoder try
-    }
-}
-
-auto ext_supported = [](const std::string &e) {
-    // keep in sync with usage: "supported audio formats: flac, mp3, ogg, wav"
-    return e == ".wav" || e == ".mp3" || e == ".flac" || e == ".ogg";
-};
-
-if (fname_inp != "-" && !ext.empty() && !ext_supported(ext)) {
-    fprintf(stderr,
-        "error: unsupported audio extension '%s' for '%s'.\n"
-        "supported: flac, mp3, ogg, wav.\n"
-        "hint: convert with ffmpeg, e.g.:\n"
-        "      ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
-        ext.c_str(), fname_inp.c_str(), fname_inp.c_str());
-    continue;
-}
+        if (!validate_audio_extension(fname_inp)) {
+            continue;
+        }
 
-// Try to read/decode the audio. If it fails, give an actionable hint.
-if (!::read_audio_data(fname_inp, pcmf32, pcmf32s, params.diarize)) {
-    std::string det = ext.empty() ? "" : (" (detected extension: " + ext + ")");
-    fprintf(stderr,
-        "error: failed to decode audio from '%s'%s.\n"
-        "Make sure the file is not corrupted and has one of: flac, mp3, ogg, wav.\n"
-        "If you still hit this, convert to a standard WAV with:\n"
-        "  ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
-        fname_inp.c_str(), det.c_str(), fname_inp.c_str());
-    continue;
-}
+        // Try to read/decode the audio. If it fails, give an actionable hint.
+        if (!::read_audio_data(fname_inp, pcmf32, pcmf32s, params.diarize)) {
+            fprintf(stderr,
+                "error: failed to decode audio from '%s'.\n"
+                "Make sure the file is not corrupted and has one of: flac, mp3, ogg, wav.\n"
+                "If you still hit this, convert to a standard WAV with:\n"
+                "  ffmpeg -i \"%s\" -ar 16000 -ac 1 -c:a pcm_s16le out.wav\n",
+                fname_inp.c_str(), fname_inp.c_str());
+            continue;
+        }
 
         if (!whisper_is_multilingual(ctx)) {
             if (params.language != "en" || params.translate) {

I have refactored the extension check into validate_audio_extension(), simplified the decode-failed message, and guarded timings with processed_any. The diff is now minimal and free of formatting changes. When you have a moment, could you take another look? I’m excited to keep contributing and can iterate quickly on any feedback!!!!

[aryanrahar]

??

[aryanrahar]

can you approve the workflows?