avformat/matroskadec: Support ContentCompression for all codecs

The Matroska demuxer has three functions for creating packets out of
the data read: One for certain RealAudio codecs (ATRAC3, cook, sipr,
RealAudio 28.8), one for WebVTT (actually, the WebM flavour of it) and
one for all the others. Only the last function supported Matroska's
ContentCompression (e.g. it reversed zlib compression or added the
removed headers to the packets). But in Matroska, all tracks are allowed
to be compressed. This commit adds support for this.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/matroskadec.c

@@ -3192,10 +3192,11 @@ static int matroska_parse_rm_audio(MatroskaDemuxContext *matroska,
 }
 
 /* reconstruct full wavpack blocks from mangled matroska ones */
-static int matroska_parse_wavpack(MatroskaTrack *track, uint8_t *src,
-                                  uint8_t **pdst, int *size)
+static int matroska_parse_wavpack(MatroskaTrack *track,
+                                  uint8_t **data, int *size)
 {
     uint8_t *dst = NULL;
+    uint8_t *src = *data;
     int dstlen   = 0;
     int srclen   = *size;
     uint32_t samples;
@@ -3265,7 +3266,7 @@ static int matroska_parse_wavpack(MatroskaTrack *track, uint8_t *src,
 
     memset(dst + dstlen, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 
-    *pdst = dst;
+    *data = dst;
     *size = dstlen;
 
     return 0;
@@ -3275,8 +3276,8 @@ fail:
     return ret;
 }
 
-static int matroska_parse_prores(MatroskaTrack *track, uint8_t *src,
-                                 uint8_t **pdst, int *size)
+static int matroska_parse_prores(MatroskaTrack *track,
+                                 uint8_t **data, int *size)
 {
     uint8_t *dst;
     int dstlen = *size + 8;
@@ -3287,10 +3288,10 @@ static int matroska_parse_prores(MatroskaTrack *track, uint8_t *src,
 
         AV_WB32(dst, dstlen);
         AV_WB32(dst + 4, MKBETAG('i', 'c', 'p', 'f'));
-        memcpy(dst + 8, src, dstlen - 8);
+        memcpy(dst + 8, *data, dstlen - 8);
         memset(dst + dstlen, 0, AV_INPUT_BUFFER_PADDING_SIZE);
 
-    *pdst = dst;
+    *data = dst;
     *size = dstlen;
 
     return 0;
@@ -3413,54 +3414,46 @@ static int matroska_parse_webvtt(MatroskaDemuxContext *matroska,
 
 static int matroska_parse_frame(MatroskaDemuxContext *matroska,
                                 MatroskaTrack *track, AVStream *st,
-                                AVBufferRef *buf, uint8_t *data, int pkt_size,
+                                AVBufferRef *buf, uint8_t **data, int pkt_size,
                                 uint64_t timecode, uint64_t lace_duration,
                                 int64_t pos, int is_keyframe,
                                 uint8_t *additional, uint64_t additional_id, int additional_size,
                                 int64_t discard_padding)
 {
-    uint8_t *pkt_data = data;
+    uint8_t *pkt_data = *data;
     int res = 0;
     AVPacket pktl, *pkt = &pktl;
 
-    if (track->needs_decoding) {
-        res = matroska_decode_buffer(&pkt_data, &pkt_size, track);
-        if (res < 0)
-            return res;
-    }
-
     if (st->codecpar->codec_id == AV_CODEC_ID_WAVPACK) {
-        uint8_t *wv_data;
-        res = matroska_parse_wavpack(track, pkt_data, &wv_data, &pkt_size);
+        res = matroska_parse_wavpack(track, &pkt_data, &pkt_size);
         if (res < 0) {
             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Error parsing a wavpack block.\n");
             goto fail;
         }
-        if (pkt_data != data)
-            av_freep(&pkt_data);
-        pkt_data = wv_data;
+        if (!buf)
+            av_freep(data);
+        buf = NULL;
     }
 
     if (st->codecpar->codec_id == AV_CODEC_ID_PRORES &&
         AV_RB32(pkt_data + 4)  != MKBETAG('i', 'c', 'p', 'f')) {
-        uint8_t *pr_data;
-        res = matroska_parse_prores(track, pkt_data, &pr_data, &pkt_size);
+        res = matroska_parse_prores(track, &pkt_data, &pkt_size);
         if (res < 0) {
             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Error parsing a prores block.\n");
             goto fail;
         }
-        if (pkt_data != data)
-            av_freep(&pkt_data);
-        pkt_data = pr_data;
+        if (!buf)
+            av_freep(data);
+        buf = NULL;
     }
 
     if (!pkt_size && !additional_size)
         goto no_output;
 
     av_init_packet(pkt);
-    if (pkt_data != data)
+    if (!buf)
         pkt->buf = av_buffer_create(pkt_data, pkt_size + AV_INPUT_BUFFER_PADDING_SIZE,
                                     NULL, NULL, 0);
     else
@@ -3531,8 +3524,8 @@ FF_ENABLE_DEPRECATION_WARNINGS
 
 no_output:
 fail:
-    if (pkt_data != data)
-        av_freep(&pkt_data);
+    if (!buf)
+        av_freep(data);
     return res;
 }
 
@@ -3634,25 +3627,41 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, AVBufferRef *buf
 
     for (n = 0; n < laces; n++) {
         int64_t lace_duration = block_duration*(n+1) / laces - block_duration*n / laces;
+        uint8_t *out_data = data;
+        int      out_size = lace_size[n];
+
+        if (track->needs_decoding) {
+            res = matroska_decode_buffer(&out_data, &out_size, track);
+            if (res < 0)
+                return res;
+            /* Given that we are here means that out_data is no longer
+             * owned by buf, so set it to NULL. This depends upon
+             * zero-length header removal compression being ignored. */
+            av_assert1(out_data != data);
+            buf = NULL;
+        }
 
         if (track->audio.buf) {
-            res = matroska_parse_rm_audio(matroska, track, st, data,
-                                          lace_size[n],
+            res = matroska_parse_rm_audio(matroska, track, st,
+                                          out_data, out_size,
                                           timecode, pos);
+            if (!buf)
+                av_free(out_data);
             if (res)
                 return res;
-
         } else if (st->codecpar->codec_id == AV_CODEC_ID_WEBVTT) {
             res = matroska_parse_webvtt(matroska, track, st,
-                                        data, lace_size[n],
+                                        out_data, out_size,
                                         timecode, lace_duration,
                                         pos);
+            if (!buf)
+                av_free(out_data);
             if (res)
                 return res;
         } else {
-            res = matroska_parse_frame(matroska, track, st, buf, data, lace_size[n],
-                                       timecode, lace_duration, pos,
-                                       !n ? is_keyframe : 0,
+            res = matroska_parse_frame(matroska, track, st, buf, &out_data,
+                                       out_size, timecode, lace_duration,
+                                       pos, !n ? is_keyframe : 0,
                                        additional, additional_id, additional_size,
                                        discard_padding);
             if (res)