[FFmpeg-devel] movenc: Add support for writing st3d and sv3d boxes.

From 8eb03f706e5c490be7a9644018dd3efaf0154a81 Mon Sep 17 00:00:00 2001
From: Aaron Colwell <acolwell@google.com>
Date: Fri, 27 Jan 2017 10:07:44 -0800
Subject: [PATCH] movenc: Add support for writing st3d and sv3d boxes.

Adding support for writing spherical metadata in MP4 files.
---
 libavformat/movenc.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index dc19838ed6..aa9ee2cccd 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1603,6 +1603,92 @@  static int mov_write_subtitle_tag(AVIOContext *pb, MOVTrack *track)
     return update_size(pb, pos);
 }
 
+static int mov_write_st3d_tag(AVIOContext *pb, AVStereo3D *stereo_3d)
+{
+    int8_t stereo_mode;
+
+    if (stereo_3d->flags != 0) {
+        av_log(pb, AV_LOG_WARNING, "Unsupported stereo_3d flags %x. st3d not written.\n", stereo_3d->flags);
+        return 0;
+    }
+
+    switch (stereo_3d->type) {
+    case AV_STEREO3D_2D:
+        stereo_mode = 0;
+        break;
+    case AV_STEREO3D_TOPBOTTOM:
+        stereo_mode = 1;
+        break;
+    case AV_STEREO3D_SIDEBYSIDE:
+        stereo_mode = 2;
+        break;
+    default:
+        av_log(pb, AV_LOG_WARNING, "Unsupported stereo_3d type %d. st3d not written.\n", stereo_3d->type);
+        return 0;
+    }
+    avio_wb32(pb, 13); /* size */
+    ffio_wfourcc(pb, "st3d");
+    avio_wb32(pb, 0); /* version = 0 & flags = 0 */
+    avio_w8(pb, stereo_mode);
+    return 13;
+}
+
+static int mov_write_sv3d_tag(AVIOContext *pb, AVSphericalMapping *spherical_mapping)
+{
+    int64_t sv3d_pos = avio_tell(pb);
+    int64_t svhd_pos, proj_pos;
+
+    if (spherical_mapping->projection != AV_SPHERICAL_EQUIRECTANGULAR &&
+        spherical_mapping->projection != AV_SPHERICAL_CUBEMAP) {
+        av_log(pb, AV_LOG_WARNING, "Unsupported projection %d. sv3d not written.\n",
+               spherical_mapping->projection);
+        return 0;
+    }
+
+    avio_wb32(pb, 0);  /* size */
+    ffio_wfourcc(pb, "sv3d");
+
+    svhd_pos = avio_tell(pb);
+    avio_wb32(pb, 0);  /* size */
+    ffio_wfourcc(pb, "svhd");
+    avio_wb32(pb, 0); /* version = 0 & flags = 0 */
+    avio_put_str(pb, LIBAVFORMAT_IDENT); /* metadata_source */
+    update_size(pb, svhd_pos);
+
+    proj_pos = avio_tell(pb);
+    avio_wb32(pb, 0); /* size */
+    ffio_wfourcc(pb, "proj");
+
+    avio_wb32(pb, 24); /* size */
+    ffio_wfourcc(pb, "prhd");
+    avio_wb32(pb, 0); /* version = 0 & flags = 0 */
+    avio_wb32(pb, spherical_mapping->yaw);
+    avio_wb32(pb, spherical_mapping->pitch);
+    avio_wb32(pb, spherical_mapping->roll);
+
+    switch (spherical_mapping->projection) {
+    case AV_SPHERICAL_EQUIRECTANGULAR:
+        avio_wb32(pb, 28);    /* size */
+        ffio_wfourcc(pb, "equi");
+        avio_wb32(pb, 0); /* version = 0 & flags = 0 */
+        avio_wb32(pb, 0); /* projection_bounds_top */
+        avio_wb32(pb, 0); /* projection_bounds_bottom */
+        avio_wb32(pb, 0); /* projection_bounds_left */
+        avio_wb32(pb, 0); /* projection_bounds_right */
+        break;
+    case AV_SPHERICAL_CUBEMAP:
+        avio_wb32(pb, 20);    /* size */
+        ffio_wfourcc(pb, "cbmp");
+        avio_wb32(pb, 0); /* version = 0 & flags = 0 */
+        avio_wb32(pb, 0); /* layout */
+        avio_wb32(pb, 0); /* padding */
+        break;
+    }
+    update_size(pb, proj_pos);
+
+    return update_size(pb, sv3d_pos);
+}
+
 static int mov_write_pasp_tag(AVIOContext *pb, MOVTrack *track)
 {
     AVRational sar;
@@ -1748,6 +1834,7 @@  static int mov_write_video_tag(AVIOContext *pb, MOVMuxContext *mov, MOVTrack *tr
     int64_t pos = avio_tell(pb);
     char compressor_name[32] = { 0 };
     int avid = 0;
+    AVSphericalMapping* spherical_mapping;
 
     avio_wb32(pb, 0); /* size */
     if (mov->encryption_scheme != MOV_ENC_NONE) {
@@ -1873,6 +1960,14 @@  static int mov_write_video_tag(AVIOContext *pb, MOVMuxContext *mov, MOVTrack *tr
             av_log(mov->fc, AV_LOG_WARNING, "Not writing 'colr' atom. Format is not MOV or MP4.\n");
     }
 
+    spherical_mapping = (AVSphericalMapping*)av_stream_get_side_data(track->st, AV_PKT_DATA_SPHERICAL, NULL);
+    if (spherical_mapping) {
+        AVStereo3D* stereo_3d = (AVStereo3D*) av_stream_get_side_data(track->st, AV_PKT_DATA_STEREO3D, NULL);
+        if (stereo_3d)
+            mov_write_st3d_tag(pb, stereo_3d);
+        mov_write_sv3d_tag(pb, spherical_mapping);
+    }
+
     if (track->par->sample_aspect_ratio.den && track->par->sample_aspect_ratio.num) {
         mov_write_pasp_tag(pb, track);
     }
-- 
2.11.0.483.g087da7b7c-goog