diff mbox

[FFmpeg-devel] lavf/matroska: expose stream encoding as global side-data

Message ID 20160913024514.70435-1-rodger.combs@gmail.com
State Rejected, archived
Headers show

Commit Message

Rodger Combs Sept. 13, 2016, 2:45 a.m. UTC 
Some demuxers can't handle Matroska compression, so this lets API users
check if a file uses it and determine whether those players will fail.

Currently only exports the first encoding; the format technically supports
multiple, but I can't find an example of this and lavf doesn't support it.
---
 doc/APIchanges            |  4 ++++
 libavcodec/avcodec.h      | 43 ++++++++++++++++++++++++++++++++++++++++++-
 libavcodec/avpacket.c     |  1 +
 libavcodec/version.h      |  4 ++--
 libavformat/matroskadec.c | 23 +++++++++++++++++------
 5 files changed, 66 insertions(+), 9 deletions(-)

Comments

Hendrik Leppkes Sept. 13, 2016, 7:23 a.m. UTC | #1 
On Tue, Sep 13, 2016 at 4:45 AM, Rodger Combs <rodger.combs@gmail.com> wrote:
> Some demuxers can't handle Matroska compression, so this lets API users
> check if a file uses it and determine whether those players will fail.
>
> Currently only exports the first encoding; the format technically supports
> multiple, but I can't find an example of this and lavf doesn't support it.


I'm not really a fan of having a global side data thats specific to
one format, and not even useful beyond conveying information to a user
(which a log message could do). Can't you just export a string in
metadata or something? That way it ends up self-contained in matroska.

- Hendrik
Michael Niedermayer Sept. 13, 2016, 8:18 a.m. UTC | #2 
Hi

On Mon, Sep 12, 2016 at 09:45:14PM -0500, Rodger Combs wrote:
> Some demuxers can't handle Matroska compression, so this lets API users
> check if a file uses it and determine whether those players will fail.

I think this should be usig AV_OPT_FLAG_READONLY instead of side data

[...]
diff mbox

Patch

diff --git a/doc/APIchanges b/doc/APIchanges
index 7ac809c..144bfac 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -15,6 +15,10 @@  libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2016-09-12 - xxxxxxx - lavc 57.56.100 - avcodec.h
+  Add AVMatroskaEncoding and its constituent enums
+  (AVMatroskaEncodingType and AVMatroskaEncodingAlgorithm)
+
 2016-08-29 - 4493390 - lavfi 6.58.100 - avfilter.h
   Add AVFilterContext.nb_threads.
 
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 01f9b29..4cca01f 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1330,6 +1330,42 @@  typedef struct AVCPBProperties {
     uint64_t vbv_delay;
 } AVCPBProperties;
 
+/**
+ * Basic type of encoding in a Matroska stream
+ */
+typedef enum AVMatroskaEncodingType {
+    AV_MATROSKA_ENCODING_COMPRESSION = 0,
+    AV_MATROSKA_ENCODING_ENCRYPTION = 1,
+} AVMatroskaEncodingType;
+
+/**
+ * Encoding algorithm in a Matroska stream
+ */
+typedef enum AVMatroskaEncodingAlgorithm {
+    // Compression
+    AV_MATROSKA_ENCODING_ZLIB = 0,
+    AV_MATROSKA_ENCODING_BZLIB = 1,
+    AV_MATROSKA_ENCODING_LZO1X = 2,
+    AV_MATROSKA_ENCODING_HEADERSTRIPPING = 3,
+    // Encryption
+    AV_MATROSKA_ENCODING_SIGNING = 0,
+    AV_MATROSKA_ENCODING_DES = 1,
+    AV_MATROSKA_ENCODING_3DES = 2,
+    AV_MATROSKA_ENCODING_TWOFISH = 3,
+    AV_MATROSKA_ENCODING_BLOWFISH = 4,
+    AV_MATROSKA_ENCODING_AES = 5,
+} AVMatroskaEncodingAlgorithm;
+
+/**
+ * This structure describes the Matroska encoding (compression or encryption) applied to
+ * a stream. It can be useful when determining whether or not other demuxers can handle
+ * a file, since some players don't support header compression.
+ */
+typedef struct AVMatroskaEncoding {
+    AVMatroskaEncodingType type;
+    AVMatroskaEncodingAlgorithm algorithm;
+} AVMatroskaEncoding;
+
 #if FF_API_QSCALE_TYPE
 #define FF_QSCALE_TYPE_MPEG1 0
 #define FF_QSCALE_TYPE_MPEG2 1
@@ -1525,7 +1561,12 @@  enum AVPacketSideDataType {
      * should be associated with a video stream and containts data in the form
      * of the AVMasteringDisplayMetadata struct.
      */
-    AV_PKT_DATA_MASTERING_DISPLAY_METADATA
+    AV_PKT_DATA_MASTERING_DISPLAY_METADATA,
+
+    /**
+     * Corresponds to the AVMatroskaEncoding struct.
+     */
+    AV_PKT_DATA_MATROSKA_ENCODING,
 };
 
 #define AV_PKT_DATA_QUALITY_FACTOR AV_PKT_DATA_QUALITY_STATS //DEPRECATED
diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index fa2844d..220e305 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -367,6 +367,7 @@  const char *av_packet_side_data_name(enum AVPacketSideDataType type)
     case AV_PKT_DATA_METADATA_UPDATE:            return "Metadata Update";
     case AV_PKT_DATA_MPEGTS_STREAM_ID:           return "MPEGTS Stream ID";
     case AV_PKT_DATA_MASTERING_DISPLAY_METADATA: return "Mastering display metadata";
+    case AV_PKT_DATA_MATROSKA_ENCODING:          return "Matroska Encoding";
     }
     return NULL;
 }
diff --git a/libavcodec/version.h b/libavcodec/version.h
index f5dd118..ecd48c5 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -28,8 +28,8 @@ 
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  57
-#define LIBAVCODEC_VERSION_MINOR  55
-#define LIBAVCODEC_VERSION_MICRO 101
+#define LIBAVCODEC_VERSION_MINOR  56
+#define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 77b8a5d..9bae9c8 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1919,6 +1919,10 @@  static int matroska_parse_tracks(AVFormatContext *s)
         if (!track->codec_id)
             continue;
 
+        st = track->stream = avformat_new_stream(s, NULL);
+        if (!st)
+            return AVERROR(ENOMEM);
+
         if (track->audio.samplerate < 0 || track->audio.samplerate > INT_MAX ||
             isnan(track->audio.samplerate)) {
             av_log(matroska->ctx, AV_LOG_WARNING,
@@ -1944,7 +1948,16 @@  static int matroska_parse_tracks(AVFormatContext *s)
             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Multiple combined encodings not supported");
         } else if (encodings_list->nb_elem == 1) {
+            AVMatroskaEncoding *side_data = (void*)av_stream_new_side_data(st,
+                                                     AV_PKT_DATA_MATROSKA_ENCODING,
+                                                     sizeof(AVMatroskaEncoding));
+            if (!side_data)
+                return AVERROR(ENOMEM);
+
+            side_data->type = encodings[0].type;
+
             if (encodings[0].type) {
+                side_data->algorithm = encodings[0].encryption.algo;
                 if (encodings[0].encryption.key_id.size > 0) {
                     /* Save the encryption key id to be stored later as a
                        metadata tag. */
@@ -1972,10 +1985,12 @@  static int matroska_parse_tracks(AVFormatContext *s)
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_LZO   &&
 #endif
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_HEADERSTRIP) {
+                side_data->algorithm = encodings[0].compression.algo;
                 encodings[0].scope = 0;
                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Unsupported encoding type");
             } else if (track->codec_priv.size && encodings[0].scope & 2) {
+                side_data->algorithm = encodings[0].compression.algo;
                 uint8_t *codec_priv = track->codec_priv.data;
                 int ret = matroska_decode_buffer(&track->codec_priv.data,
                                                  &track->codec_priv.size,
@@ -1989,6 +2004,8 @@  static int matroska_parse_tracks(AVFormatContext *s)
 
                 if (codec_priv != track->codec_priv.data)
                     av_free(codec_priv);
+            } else {
+                side_data->algorithm = encodings[0].compression.algo;
             }
         }
 
@@ -2000,12 +2017,6 @@  static int matroska_parse_tracks(AVFormatContext *s)
             }
         }
 
-        st = track->stream = avformat_new_stream(s, NULL);
-        if (!st) {
-            av_free(key_id_base64);
-            return AVERROR(ENOMEM);
-        }
-
         if (key_id_base64) {
             /* export encryption key id as base64 metadata tag */
             av_dict_set(&st->metadata, "enc_key_id", key_id_base64, 0);