ffmpeg: factorize process_input() out

Based-on:
	commit 0c00fd80ee4791bd70b634084307fc9f179e0412
	Author: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -2691,64 +2691,37 @@ static void reset_eagain(void)
         input_files[i]->eagain = 0;
 }
 
-/*
+/**
- * The following code is the main loop of the file converter
+ * @return
+ * - 0 -- one packet was read and processed
+ * - AVERROR(EAGAIN) -- no packets were available for selected file,
+ *   this function should be called again
+ * - AVERROR_EOF -- this function should not be called again
  */
-static int transcode(void)
+static int process_input(void)
 {
-    int ret, i;
-    AVFormatContext *is, *os;
-    OutputStream *ost;
-    InputStream *ist;
-    int64_t timer_start;
-
-    ret = transcode_init();
-    if (ret < 0)
-        goto fail;
-
-    if (stdin_interaction) {
-        av_log(NULL, AV_LOG_INFO, "Press [q] to stop, [?] for help\n");
-    }
-
-    timer_start = av_gettime();
-
-#if HAVE_PTHREADS
-    if ((ret = init_input_threads()) < 0)
-        goto fail;
-#endif
-
-    while (!received_sigterm) {
     InputFile *ifile;
+    AVFormatContext *is;
+    InputStream *ist;
     AVPacket pkt;
+    int ret, i, j;
     int file_index;
-        int64_t cur_time= av_gettime();
-
-        /* if 'q' pressed, exits */
-        if (stdin_interaction)
-            if (check_keyboard_interaction(cur_time) < 0)
-                break;
-
-        /* check if there's any stream where output is still needed */
-        if (!need_output()) {
-            av_log(NULL, AV_LOG_VERBOSE, "No more output streams to write to, finishing.\n");
-            break;
-        }
 
     /* select the stream that we must read now */
     file_index = select_input_file();
     /* if none, if is finished */
     if (file_index == -2) {
         poll_filters() ;
-            continue;
+        return AVERROR(EAGAIN);
     }
     if (file_index < 0) {
         if (got_eagain()) {
             reset_eagain();
             av_usleep(10000);
-                continue;
+            return AVERROR(EAGAIN);
         }
         av_log(NULL, AV_LOG_VERBOSE, "No more inputs to read from, finishing.\n");
-            break;
+        return AVERROR_EOF;
     }
     ifile = input_files[file_index];
 
@@ -2757,7 +2730,7 @@ static int transcode(void)
 
     if (ret == AVERROR(EAGAIN)) {
         ifile->eagain = 1;
-            continue;
+        return ret;
     }
     if (ret < 0) {
         if (ret != AVERROR_EOF) {
@@ -2775,9 +2748,9 @@ static int transcode(void)
         }
 
         if (opt_shortest)
-                break;
+            return AVERROR_EOF;
         else
-                continue;
+            return AVERROR(EAGAIN);
     }
 
     reset_eagain();
@@ -2832,7 +2805,8 @@ static int transcode(void)
                 input_files[ist->file_index]->ts_offset);
     }
 
-        if (pkt.dts != AV_NOPTS_VALUE && ist->next_dts != AV_NOPTS_VALUE && !copy_ts) {
+    if (pkt.dts != AV_NOPTS_VALUE && ist->next_dts != AV_NOPTS_VALUE &&
+        !copy_ts) {
         int64_t pkt_dts = av_rescale_q(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q);
         int64_t delta   = pkt_dts - ist->next_dts;
         if (is->iformat->flags & AVFMT_TS_DISCONT) {
@@ -2844,9 +2818,9 @@ static int transcode(void)
             av_log(NULL, AV_LOG_DEBUG,
                    "timestamp discontinuity %"PRId64", new offset= %"PRId64"\n",
                    delta, ifile->ts_offset);
-                pkt.dts-= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
+            pkt.dts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
             if (pkt.pts != AV_NOPTS_VALUE)
-                    pkt.pts-= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
+                pkt.pts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
         }
         } else {
             if ( delta < -1LL*dts_error_threshold*AV_TIME_BASE ||
@@ -2879,12 +2853,65 @@ static int transcode(void)
         if (exit_on_error)
             exit_program(1);
         av_free_packet(&pkt);
-            continue;
+        return AVERROR(EAGAIN);
     }
 
-    discard_packet:
+discard_packet:
     av_free_packet(&pkt);
 
+    return 0;
+}
+
+/*
+ * The following code is the main loop of the file converter
+ */
+static int transcode(void)
+{
+    int ret, i;
+    AVFormatContext *os;
+    OutputStream *ost;
+    InputStream *ist;
+    int64_t timer_start;
+
+    ret = transcode_init();
+    if (ret < 0)
+        goto fail;
+
+    if (stdin_interaction) {
+        av_log(NULL, AV_LOG_INFO, "Press [q] to stop, [?] for help\n");
+    }
+
+    timer_start = av_gettime();
+
+#if HAVE_PTHREADS
+    if ((ret = init_input_threads()) < 0)
+        goto fail;
+#endif
+
+    while (!received_sigterm) {
+        int64_t cur_time= av_gettime();
+
+        /* if 'q' pressed, exits */
+        if (stdin_interaction)
+            if (check_keyboard_interaction(cur_time) < 0)
+                break;
+
+        /* check if there's any stream where output is still needed */
+        if (!need_output()) {
+            av_log(NULL, AV_LOG_VERBOSE, "No more output streams to write to, finishing.\n");
+            break;
+        }
+
+        ret = process_input();
+        if (ret < 0) {
+            if (ret == AVERROR(EAGAIN))
+                continue;
+            if (ret == AVERROR_EOF)
+                break;
+            av_log(NULL, AV_LOG_ERROR, "Error while filtering.\n");
+            break;
+        }
+
         /* dump report by using the output first video and audio streams */
         print_report(0, timer_start, cur_time);
     }