avimux: support (some) VBR audio muxing

AVI format can handle VBR audio provided audio chunks are of fixed duration
(cfr fixed duration video frames).  Apply this approach to (always) parsed
raw AAC and (if parsed) to MPEG-1/2 audio.

See #368681.

diff --git a/gst/avi/gstavimux.c b/gst/avi/gstavimux.c
index 0602e41..584f0e7 100644 (file)
--- a/gst/avi/gstavimux.c
+++ b/gst/avi/gstavimux.c
@@ -636,6 +636,96 @@ refuse_caps:
   }
 }
 
+static GstFlowReturn
+gst_avi_mux_audsink_scan_mpeg_audio (GstAviMux * avimux, GstAviPad * avipad,
+    GstBuffer * buffer)
+{
+  guint8 *data;
+  guint size;
+  guint spf;
+  guint32 header;
+  gulong layer;
+  gulong version;
+  gint lsf, mpg25;
+
+  data = GST_BUFFER_DATA (buffer);
+  size = GST_BUFFER_SIZE (buffer);
+
+  if (size < 4)
+    goto not_parsed;
+
+  header = GST_READ_UINT32_BE (data);
+
+  if ((header & 0xffe00000) != 0xffe00000)
+    goto not_parsed;
+
+  /* thanks go to mp3parse */
+  if (header & (1 << 20)) {
+    lsf = (header & (1 << 19)) ? 0 : 1;
+    mpg25 = 0;
+  } else {
+    lsf = 1;
+    mpg25 = 1;
+  }
+
+  version = 1 + lsf + mpg25;
+  layer = 4 - ((header >> 17) & 0x3);
+
+  /* see http://www.codeproject.com/audio/MPEGAudioInfo.asp */
+  if (layer == 1)
+    spf = 384;
+  else if (layer == 2)
+    spf = 1152;
+  else if (version == 1) {
+    spf = 1152;
+  } else {
+    /* MPEG-2 or "2.5" */
+    spf = 576;
+  }
+
+  if (G_UNLIKELY (avipad->hdr.scale <= 1))
+    avipad->hdr.scale = spf;
+  else if (G_UNLIKELY (avipad->hdr.scale != spf)) {
+    GST_WARNING_OBJECT (avimux, "input mpeg audio has varying frame size");
+    goto cbr_fallback;
+  }
+
+  return GST_FLOW_OK;
+
+  /* EXITS */
+not_parsed:
+  {
+    GST_WARNING_OBJECT (avimux, "input mpeg audio is not parsed");
+    /* fall-through */
+  }
+cbr_fallback:
+  {
+    GST_WARNING_OBJECT (avimux, "falling back to CBR muxing");
+    avipad->hdr.scale = 1;
+    /* no need to check further */
+    avipad->hook = NULL;
+    return GST_FLOW_OK;
+  }
+}
+
+static void
+gst_avi_mux_audsink_set_fields (GstAviMux * avimux, GstAviAudioPad * avipad)
+{
+  if (avipad->parent.hdr.scale > 1) {
+    /* vbr case: fixed duration per frame/chunk */
+    avipad->parent.hdr.rate = avipad->auds.rate;
+    avipad->parent.hdr.samplesize = 0;
+    /* FIXME ?? some rumours say this should be largest audio chunk size */
+    avipad->auds.blockalign = avipad->parent.hdr.scale;
+  } else {
+    /* by spec, hdr.rate is av_bps related, is calculated that way in stop_file,
+     * and reduces to sample rate in PCM like cases */
+    avipad->parent.hdr.rate = avipad->auds.av_bps / avipad->auds.blockalign;
+    avipad->parent.hdr.samplesize = avipad->auds.blockalign;
+    avipad->parent.hdr.scale = 1;
+  }
+}
+
 static gboolean
 gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
 {
@@ -729,8 +819,10 @@ gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
       switch (mpegversion) {
         case 1:{
           gint layer = 3;
+          gboolean parsed = FALSE;
 
           gst_structure_get_int (structure, "layer", &layer);
+          gst_structure_get_boolean (structure, "parsed", &parsed);
           switch (layer) {
             case 3:
               avipad->auds.format = GST_RIFF_WAVE_FORMAT_MPEGL3;
@@ -740,12 +832,32 @@ gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
               avipad->auds.format = GST_RIFF_WAVE_FORMAT_MPEGL12;
               break;
           }
+          if (parsed) {
+            /* treat as VBR, should also cover CBR case;
+             * setup hook to parse frame header and determine spf */
+            avipad->parent.hook = gst_avi_mux_audsink_scan_mpeg_audio;
+          } else {
+            GST_WARNING_OBJECT (avimux, "unparsed MPEG audio input (?), "
+                "doing CBR muxing");
+          }
           break;
         }
         case 4:
-          GST_WARNING ("AAC");
+        {
+          GstBuffer *codec_data_buf = avipad->auds_codec_data;
+          guint codec;
+
+          /* vbr case needs some special handling */
+          if (!codec_data_buf || GST_BUFFER_SIZE (codec_data_buf) < 2) {
+            GST_WARNING_OBJECT (avimux, "no (valid) codec_data for AAC audio");
+            break;
+          }
           avipad->auds.format = GST_RIFF_WAVE_FORMAT_AAC;
+          /* need to determine frame length */
+          codec = GST_READ_UINT16_BE (GST_BUFFER_DATA (codec_data_buf));
+          avipad->parent.hdr.scale = (codec & 0x4) ? 960 : 1024;
           break;
+        }
       }
     } else if (!strcmp (mimetype, "audio/x-vorbis")) {
       avipad->auds.format = GST_RIFF_WAVE_FORMAT_VORBIS3;
@@ -793,11 +905,7 @@ gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
   if (!avipad->auds.format)
     goto refuse_caps;
 
-  /* by spec, hdr.rate is av_bps related, is calculated that way in stop_file,
-   * and reduces to sample rate in PCM like cases */
-  avipad->parent.hdr.rate = avipad->auds.av_bps / avipad->auds.blockalign;
-  avipad->parent.hdr.samplesize = avipad->auds.blockalign;
-  avipad->parent.hdr.scale = 1;
+  gst_avi_mux_audsink_set_fields (avimux, avipad);
 
   gst_object_unref (avimux);
   return TRUE;
@@ -1667,10 +1775,11 @@ gst_avi_mux_stop_file (GstAviMux * avimux)
               (NULL));
           audpad->auds.av_bps = 0;
         }
-        avipad->hdr.rate = audpad->auds.av_bps * avipad->hdr.scale;
       }
+      gst_avi_mux_audsink_set_fields (avimux, audpad);
       avimux->avi_hdr.max_bps += audpad->auds.av_bps;
-      avipad->hdr.length = (audpad->audio_time * avipad->hdr.rate) / GST_SECOND;
+      avipad->hdr.length = gst_util_uint64_scale (audpad->audio_time,
+          avipad->hdr.rate, avipad->hdr.scale * GST_SECOND);
     } else {
       GstAviVideoPad *vidpad = (GstAviVideoPad *) avipad;
 
@@ -1802,6 +1911,9 @@ gst_avi_mux_do_buffer (GstAviMux * avimux, GstAviPad * avipad)
     avimux->data_size += total_size;
   }
 
+  if (G_UNLIKELY (avipad->hook))
+    avipad->hook (avimux, avipad, data);
+
   if (avipad->is_video) {
     /* the suggested buffer size is the max frame size */
     if (avipad->hdr.bufsize < GST_BUFFER_SIZE (data))

diff --git a/gst/avi/gstavimux.h b/gst/avi/gstavimux.h
index 0cc6908..24e427b 100644 (file)
--- a/gst/avi/gstavimux.h
+++ b/gst/avi/gstavimux.h
@@ -64,7 +64,14 @@ typedef struct _gst_riff_strh_full {
   gint16  bottom;
 } gst_riff_strh_full;
 
-typedef struct _GstAviPad {
+typedef struct _GstAviPad GstAviPad;
+typedef struct _GstAviMux GstAviMux;
+typedef struct _GstAviMuxClass GstAviMuxClass;
+
+typedef GstFlowReturn (*GstAviPadHook) (GstAviMux * avi, GstAviPad * avipad,
+                                        GstBuffer * buffer);
+
+struct _GstAviPad {
   /* do not extend, link to it */
   /* is NULL if original sink request pad has been removed */
   GstCollectData *collect;
@@ -83,7 +90,10 @@ typedef struct _GstAviPad {
   gst_avi_superindex_entry idx[GST_AVI_SUPERINDEX_COUNT];
   gint idx_index;
   gchar *idx_tag;
-} GstAviPad;
+
+  /* stream specific hook */
+  GstAviPadHook hook;
+};
 
 typedef struct _GstAviVideoPad {
   GstAviPad parent;
@@ -116,9 +126,6 @@ typedef struct _GstAviCollectData {
   GstAviPad      *avipad;
 } GstAviCollectData;
 
-typedef struct _GstAviMux GstAviMux;
-typedef struct _GstAviMuxClass GstAviMuxClass;
-
 struct _GstAviMux {
   GstElement element;