Clean up ffprobe error reporting

The error messages were a bit difficult for users to understand due to a
combination of including useless technical information and lacking
userful user information.  The error messages are more verbose now and
give a better indication of what went wrong.

src/ffmpeg.js

@@ -46,15 +46,41 @@ function fixRedirectIfNeeded(urldata, redirect) {
     return redirect;
 }
 
+function translateStatusCode(statusCode) {
+    switch (statusCode) {
+        case 400:
+            return "The request for the audio/video link was rejected as invalid.  " +
+                "Contact support for troubleshooting assistance.";
+        case 401:
+        case 403:
+            return "Access to the link was denied.  Contact the owner of the " +
+                "website hosting the audio/video file to grant permission for " +
+                "the file to be downloaded.";
+        case 404:
+            return "The requested link could not be found (404).";
+        case 500:
+        case 503:
+            return "The website hosting the audio/video link encountered an error " +
+                "and was unable to process the request.  Try again in a few minutes, " +
+                "and if the issue persists, contact the owner of the website hosting " +
+                "the link.";
+        default:
+            return "An unknown issue occurred when requesting the audio/video link.  " +
+                "Contact support for troubleshooting assistance.";
+    }
+}
+
 function testUrl(url, cb, redirCount) {
     if (!redirCount) redirCount = 0;
     var data = urlparse.parse(url);
     if (!/https?:/.test(data.protocol)) {
-        return cb("Video links must start with http:// or https://");
+        return cb("Only links starting with 'http://' or 'https://' are supported " +
+                  "for raw audio/video support");
     }
 
     if (!data.hostname) {
-        return cb("Invalid link");
+        return cb("The link to the file is missing the website address and can't " +
+                  "be processed.");
     }
 
     var transport = (data.protocol === "https:") ? https : http;
@@ -64,29 +90,33 @@ function testUrl(url, cb, redirCount) {
 
         if (res.statusCode === 301 || res.statusCode === 302) {
             if (redirCount > 2) {
-                return cb("Too many redirects.  Please provide a direct link to the " +
+                return cb("The request for the audio/video file has been redirected " +
-                          "file");
+                          "more than twice.  This could indicate a misconfiguration " +
+                          "on the website hosting the link.  For best results, use " +
+                          "a direct link.");
             }
             return testUrl(fixRedirectIfNeeded(data, res.headers["location"]), cb,
                     redirCount + 1);
         }
 
         if (res.statusCode !== 200) {
-            var message = res.statusMessage;
+            return cb(translateStatusCode(res.statusCode));
-            if (!message) message = "";
-            return cb("HTTP " + res.statusCode + " " + message);
         }
 
         if (!/^audio|^video/.test(res.headers["content-type"])) {
-            return cb("Server did not return an audio or video file, or sent the " +
+            return cb("Expected a content-type starting with 'audio' or 'video', but " +
-                      "wrong Content-Type");
+                      "got '" + res.headers["content-type"] + "'.  Only direct links " +
+                      "to video and audio files are accepted, and the website hosting " +
+                      "the file must be configured to send the correct MIME type.");
         }
 
         cb();
     });
 
     req.on("error", function (err) {
-        cb(err);
+        cb("An unexpected error occurred while trying to process the link.  " +
+           "Try again, and contact support for further troubleshooting if the " +
+           "problem continues." + (!!err.code ? (" Error code: " + err.code) : ""));
     });
 
     req.end();
@@ -215,7 +245,9 @@ exports.ffprobe = function ffprobe(filename, cb) {
         Logger.errlog.log("Possible runaway ffprobe process for file " + filename);
         fflog("Killing ffprobe for " + filename + " after " + (TIMEOUT/1000) + " seconds");
         childErr = new Error("File query exceeded time limit of " + (TIMEOUT/1000) +
-                             " seconds");
+                             " seconds.  To avoid this issue, encode your videos " +
+                             "using the 'faststart' option: " +
+                             "https://trac.ffmpeg.org/wiki/Encode/H.264#faststartforwebvideo");
         child.kill("SIGKILL");
     }, TIMEOUT);
 
@@ -231,7 +263,9 @@ exports.ffprobe = function ffprobe(filename, cb) {
         stderr += data;
         if (stderr.match(/the tls connection was non-properly terminated/i)) {
             fflog("Killing ffprobe for " + filename + " due to TLS error");
-            childErr = new Error("Remote server closed connection unexpectedly");
+            childErr = new Error("The connection was closed unexpectedly.  " +
+                                 "If the problem continues, contact support " +
+                                 "for troubleshooting assistance.");
             child.kill("SIGKILL");
         }
     });
@@ -281,7 +315,7 @@ exports.query = function (filename, cb) {
 
     if (!filename.match(/^https?:\/\//)) {
         return cb("Raw file playback is only supported for links accessible via HTTP " +
-                  "or HTTPS");
+                  "or HTTPS.  Ensure that the link begins with 'http://' or 'https://'");
     }
 
     testUrl(filename, function (err) {
@@ -299,10 +333,11 @@ exports.query = function (filename, cb) {
                 } else if (err.message) {
                     if (err.message.match(/protocol not found/i))
                         return cb("Link uses a protocol unsupported by this server's " +
-                                  "version of ffmpeg");
+                                  "version of ffmpeg.  Some older versions of " +
+                                  "ffprobe/avprobe do not support HTTPS.");
 
                     if (err.message.match(/exceeded time limit/) ||
-                        err.message.match(/remote server closed/i)) {
+                        err.message.match(/closed unexpectedly/i)) {
                         return cb(err.message);
                     }
 
@@ -310,11 +345,15 @@ exports.query = function (filename, cb) {
                     // indicate a problem with the remote file, not with this code.
                     if (!/(av|ff)probe/.test(String(err)))
                         Logger.errlog.log(err.stack || err);
-                    return cb("Unable to query file data with ffmpeg");
+                    return cb("An unexpected error occurred while trying to process " +
+                              "the link.  Contact support for troubleshooting " +
+                              "assistance.");
                 } else {
                     if (!/(av|ff)probe/.test(String(err)))
                         Logger.errlog.log(err.stack || err);
-                    return cb("Unable to query file data with ffmpeg");
+                    return cb("An unexpected error occurred while trying to process " +
+                              "the link.  Contact support for troubleshooting " +
+                              "assistance.");
                 }
             }
 
@@ -322,7 +361,9 @@ exports.query = function (filename, cb) {
                 data = reformatData(data);
             } catch (e) {
                 Logger.errlog.log(e.stack || e);
-                return cb("Unable to query file data with ffmpeg");
+                return cb("An unexpected error occurred while trying to process " +
+                          "the link.  Contact support for troubleshooting " +
+                          "assistance.");
             }
 
             if (data.medium === "video") {

www/js/util.js

@@ -2070,7 +2070,7 @@ function queueMessage(data, type) {
     }
     var newAlert = makeAlert(title, text, type)
         .addClass("linewrap qfalert qf-" + type)
-        .appendTo($("#queuefail"));
+        .prependTo($("#queuefail"));
     newAlert.find(".alert").data("reason", data.msg);
 }