Add option to disable seeking on transcodes. (Mitigates #548 & #723)

As per #548, #723, and tsquillario/Jamstash#131, the current method of
estimating `Content-Length` creates various problems.

However, if headers such as `Accept-Ranges` is omitted, clients will only
use the first connection, which is `Transfer-Encoding: chunked`, and no
`Content-Length` is necessary.

Doing this has the side effect that (at least on the web player) seeking
to a specific time is no longer possible, thus this was made an opt-in
option.

Signed-off-by: WillyPillow <wp@nerde.pw>

airsonic-main/src/main/java/org/airsonic/player/controller/StreamController.java

@@ -152,7 +152,7 @@ public class StreamController  {
                 playQueue.addFiles(true, file);
                 player.setPlayQueue(playQueue);
 
-                if (!file.isVideo()) {
+                if (settingsService.isEnableSeek() && !file.isVideo()) {
                     response.setIntHeader("ETag", file.getId());
                     response.setHeader("Accept-Ranges", "bytes");
                 }
@@ -164,7 +164,7 @@ public class StreamController  {
                 boolean isHls = ServletRequestUtils.getBooleanParameter(request, "hls", false);
 
                 range = getRange(request, file);
-                if (range != null && !file.isVideo()) {
+                if (settingsService.isEnableSeek() && range != null && !file.isVideo()) {
                     LOG.info("Got HTTP range: " + range);
                     response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
                     Util.setContentLength(response, range.isClosed() ? range.size() : fileLength - range.getFirstBytePos());

airsonic-main/src/main/java/org/airsonic/player/controller/TranscodingSettingsController.java

@@ -56,6 +56,7 @@ public class TranscodingSettingsController {
 
         map.put("transcodings", transcodingService.getAllTranscodings());
         map.put("transcodeDirectory", transcodingService.getTranscodeDirectory());
+        map.put("enableSeek", settingsService.isEnableSeek());
         map.put("downsampleCommand", settingsService.getDownsamplingCommand());
         map.put("hlsCommand", settingsService.getHlsCommand());
         map.put("brand", settingsService.getBrand());
@@ -131,6 +132,7 @@ public class TranscodingSettingsController {
                 return error;
             }
         }
+        settingsService.setEnableSeek(request.getParameter("enableSeek") != null);
         settingsService.setDownsamplingCommand(StringUtils.trim(request.getParameter("downsampleCommand")));
         settingsService.setHlsCommand(StringUtils.trim(request.getParameter("hlsCommand")));
         settingsService.save();

airsonic-main/src/main/java/org/airsonic/player/service/SettingsService.java

@@ -83,6 +83,7 @@ public class SettingsService {
     private static final String KEY_PODCAST_EPISODE_DOWNLOAD_COUNT = "PodcastEpisodeDownloadCount";
     private static final String KEY_DOWNLOAD_BITRATE_LIMIT = "DownloadBitrateLimit";
     private static final String KEY_UPLOAD_BITRATE_LIMIT = "UploadBitrateLimit";
+    private static final String KEY_ENABLE_SEEK = "EnableSeek1";
     private static final String KEY_DOWNSAMPLING_COMMAND = "DownsamplingCommand4";
     private static final String KEY_HLS_COMMAND = "HlsCommand3";
     private static final String KEY_JUKEBOX_COMMAND = "JukeboxCommand2";
@@ -165,6 +166,7 @@ public class SettingsService {
     private static final int DEFAULT_PODCAST_EPISODE_DOWNLOAD_COUNT = 1;
     private static final long DEFAULT_DOWNLOAD_BITRATE_LIMIT = 0;
     private static final long DEFAULT_UPLOAD_BITRATE_LIMIT = 0;
+    private static final boolean DEFAULT_ENABLE_SEEK = true;
     private static final String DEFAULT_DOWNSAMPLING_COMMAND = "ffmpeg -i %s -map 0:0 -b:a %bk -v 0 -f mp3 -";
     private static final String DEFAULT_HLS_COMMAND = "ffmpeg -ss %o -t %d -i %s -async 1 -b:v %bk -s %wx%h -ar 44100 -ac 2 -v 0 -f mpegts -c:v libx264 -preset superfast -c:a libmp3lame -threads 0 -";
     private static final String DEFAULT_JUKEBOX_COMMAND = "ffmpeg -ss %o -i %s -map 0:0 -v 0 -ar 44100 -ac 2 -f s16be -";
@@ -621,6 +623,14 @@ public class SettingsService {
         setLong(KEY_UPLOAD_BITRATE_LIMIT, limit);
     }
 
+    public boolean isEnableSeek() {
+        return getBoolean(KEY_ENABLE_SEEK, DEFAULT_ENABLE_SEEK);
+    }
+
+    public void setEnableSeek(boolean enableSeek) {
+        setBoolean(KEY_ENABLE_SEEK, enableSeek);
+    }
+
     public String getDownsamplingCommand() {
         return getProperty(KEY_DOWNSAMPLING_COMMAND, DEFAULT_DOWNSAMPLING_COMMAND);
     }

airsonic-main/src/main/resources/org/airsonic/player/i18n/ResourceBundle_en.properties

@@ -418,6 +418,7 @@ transcodingsettings.step2=Step 2
 transcodingsettings.step3=Step 3
 transcodingsettings.add=Add transcoding
 transcodingsettings.defaultactive=Enable transcoding settings for all existing and new players.
+transcodingsettings.enableseek=Enable seeking on transcodes (might not work well with VBR codecs)
 transcodingsettings.recommended=Recommended configuration
 transcodingsettings.noname=Please specify a name.
 transcodingsettings.nosourceformat=Please specify the format to convert from.

airsonic-main/src/main/resources/org/airsonic/player/i18n/ResourceBundle_zh_CN.properties

@@ -385,6 +385,7 @@ transcodingsettings.step2 = \u6B65\u9AA4\u4E8C
 transcodingsettings.step3 = \u6B65\u9AA4\u4E09
 transcodingsettings.add = \u6DFB\u52A0
 transcodingsettings.defaultactive = \u4E3A\u73B0\u6709\u548C\u65B0\u64AD\u653E\u5668\u542F\u7528\u8FD9\u9879\u8F6C\u7801\u8BBE\u7F6E
+transcodingsettings.enableseek = \u542F\u7528\u5FEB\u8FDB\uFF08\u5BF9 VBR \u7F16\u7801\u76F8\u5BB9\u6027\u8F83\u5DEE\uFF09
 transcodingsettings.recommended = \u63A8\u8350\u8BBE\u7F6E
 transcodingsettings.noname = \u8BF7\u6307\u5B9A\u4E00\u4E2A\u540D\u79F0.
 transcodingsettings.nosourceformat = \u8BF7\u6307\u5B9A\u8F6C\u6362\u683C\u5F0F.

airsonic-main/src/main/resources/org/airsonic/player/i18n/ResourceBundle_zh_TW.properties

@@ -467,6 +467,7 @@ transcodingsettings.step2 = \u6B65\u9A5F\u4E8C
 transcodingsettings.step3 = \u6B65\u9A5F\u4E09
 transcodingsettings.add = \u65B0\u589E\u8F49\u78BC\u5668
 transcodingsettings.defaultactive = \u9810\u8A2D
+transcodingsettings.enableseek = \u555F\u7528\u5FEB\u9032\uFF08\u5C0D VBR \u7DE8\u78BC\u76F8\u5BB9\u6027\u8F03\u5DEE\uFF09
 transcodingsettings.recommended = \u5EFA\u8B70\u7684\u8A2D\u5B9A
 transcodingsettings.noname = \u8ACB\u6307\u5B9A\u4E00\u500B\u540D\u7A31\u3002
 transcodingsettings.nosourceformat = \u8ACB\u6307\u5B9A\u8F49\u63DB\u7684\u4F86\u6E90\u683C\u5F0F\u3002

airsonic-main/src/main/webapp/WEB-INF/jsp/transcodingSettings.jsp

@@ -59,6 +59,11 @@
 
 
     <table style="white-space:nowrap" class="indent">
+        <tr>
+            <td>
+                <input type="checkbox" id="enableSeek" name="enableSeek" class="checkbox" ${model.enableSeek ? "checked" : ""}/>
+                <label for="enableSeek"><fmt:message key="transcodingsettings.enableseek"/></label>
+            </td>
         <tr>
             <td style="font-weight: bold;">
                 <fmt:message key="advancedsettings.downsamplecommand"/>