Merge pull request #313 from pengbins:fix_ts_h265reader_parse_sps

PiperOrigin-RevId: 527259619
(cherry picked from commit fab134f0b3)

RELEASENOTES.md

@@ -8,6 +8,10 @@
     *   Fix issue where last frame may not be rendered if the last sample with
         frames is dequeued without reading the 'end of stream' sample.
         ([#11079](https://github.com/google/ExoPlayer/issues/11079)).
+*   Extractors:
+    *   Fix parsing of H.265 SPS in MPEG-TS files by re-using the parsing logic
+        already used by RTSP and MP4 extractors
+        ([#303](https://github.com/androidx/media/issues/303)).
 *   Session:
     *   Fix issue where `MediaController` doesn't update its available commands
         when connected to a legacy `MediaSessionCompat` that updates its

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/e2etest/TsPlaybackTest.java

@@ -63,6 +63,7 @@ public class TsPlaybackTest {
         "sample_h264_mpeg_audio.ts",
         "sample_h264_no_access_unit_delimiters.ts",
         "sample_h265.ts",
+        "sample_h265_rps_pred.ts",
         "sample_latm.ts",
         "sample_scte35.ts",
         "sample_with_id3.adts",

libraries/extractor/src/main/java/androidx/media3/extractor/ts/H265Reader.java

@@ -15,15 +15,12 @@
  */
 package androidx.media3.extractor.ts;
 
-import static java.lang.Math.min;
-
 import androidx.annotation.Nullable;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
 import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.CodecSpecificDataUtil;
-import androidx.media3.common.util.Log;
 import androidx.media3.common.util.ParsableByteArray;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.common.util.Util;
@@ -246,216 +243,30 @@ public final class H265Reader implements ElementaryStreamReader {
     System.arraycopy(sps.nalData, 0, csdData, vps.nalLength, sps.nalLength);
     System.arraycopy(pps.nalData, 0, csdData, vps.nalLength + sps.nalLength, pps.nalLength);
 
-    // Parse the SPS NAL unit, as per H.265/HEVC (2014) 7.3.2.2.1.
+    // Skip the 3-byte NAL unit start code synthesised by the NalUnitTargetBuffer constructor.
-    ParsableNalUnitBitArray bitArray = new ParsableNalUnitBitArray(sps.nalData, 0, sps.nalLength);
+    NalUnitUtil.H265SpsData spsData =
-    bitArray.skipBits(40 + 4); // NAL header, sps_video_parameter_set_id
+        NalUnitUtil.parseH265SpsNalUnit(sps.nalData, /* nalOffset= */ 3, sps.nalLength);
-    int maxSubLayersMinus1 = bitArray.readBits(3);
-    bitArray.skipBit(); // sps_temporal_id_nesting_flag
-    int generalProfileSpace = bitArray.readBits(2);
-    boolean generalTierFlag = bitArray.readBit();
-    int generalProfileIdc = bitArray.readBits(5);
-    int generalProfileCompatibilityFlags = 0;
-    for (int i = 0; i < 32; i++) {
-      if (bitArray.readBit()) {
-        generalProfileCompatibilityFlags |= (1 << i);
-      }
-    }
-    int[] constraintBytes = new int[6];
-    for (int i = 0; i < constraintBytes.length; ++i) {
-      constraintBytes[i] = bitArray.readBits(8);
-    }
-    int generalLevelIdc = bitArray.readBits(8);
-    int toSkip = 0;
-    for (int i = 0; i < maxSubLayersMinus1; i++) {
-      if (bitArray.readBit()) { // sub_layer_profile_present_flag[i]
-        toSkip += 89;
-      }
-      if (bitArray.readBit()) { // sub_layer_level_present_flag[i]
-        toSkip += 8;
-      }
-    }
-    bitArray.skipBits(toSkip);
-    if (maxSubLayersMinus1 > 0) {
-      bitArray.skipBits(2 * (8 - maxSubLayersMinus1));
-    }
-
-    bitArray.readUnsignedExpGolombCodedInt(); // sps_seq_parameter_set_id
-    int chromaFormatIdc = bitArray.readUnsignedExpGolombCodedInt();
-    if (chromaFormatIdc == 3) {
-      bitArray.skipBit(); // separate_colour_plane_flag
-    }
-    int picWidthInLumaSamples = bitArray.readUnsignedExpGolombCodedInt();
-    int picHeightInLumaSamples = bitArray.readUnsignedExpGolombCodedInt();
-    if (bitArray.readBit()) { // conformance_window_flag
-      int confWinLeftOffset = bitArray.readUnsignedExpGolombCodedInt();
-      int confWinRightOffset = bitArray.readUnsignedExpGolombCodedInt();
-      int confWinTopOffset = bitArray.readUnsignedExpGolombCodedInt();
-      int confWinBottomOffset = bitArray.readUnsignedExpGolombCodedInt();
-      // H.265/HEVC (2014) Table 6-1
-      int subWidthC = chromaFormatIdc == 1 || chromaFormatIdc == 2 ? 2 : 1;
-      int subHeightC = chromaFormatIdc == 1 ? 2 : 1;
-      picWidthInLumaSamples -= subWidthC * (confWinLeftOffset + confWinRightOffset);
-      picHeightInLumaSamples -= subHeightC * (confWinTopOffset + confWinBottomOffset);
-    }
-    bitArray.readUnsignedExpGolombCodedInt(); // bit_depth_luma_minus8
-    bitArray.readUnsignedExpGolombCodedInt(); // bit_depth_chroma_minus8
-    int log2MaxPicOrderCntLsbMinus4 = bitArray.readUnsignedExpGolombCodedInt();
-    // for (i = sps_sub_layer_ordering_info_present_flag ? 0 : sps_max_sub_layers_minus1; ...)
-    for (int i = bitArray.readBit() ? 0 : maxSubLayersMinus1; i <= maxSubLayersMinus1; i++) {
-      bitArray.readUnsignedExpGolombCodedInt(); // sps_max_dec_pic_buffering_minus1[i]
-      bitArray.readUnsignedExpGolombCodedInt(); // sps_max_num_reorder_pics[i]
-      bitArray.readUnsignedExpGolombCodedInt(); // sps_max_latency_increase_plus1[i]
-    }
-    bitArray.readUnsignedExpGolombCodedInt(); // log2_min_luma_coding_block_size_minus3
-    bitArray.readUnsignedExpGolombCodedInt(); // log2_diff_max_min_luma_coding_block_size
-    bitArray.readUnsignedExpGolombCodedInt(); // log2_min_luma_transform_block_size_minus2
-    bitArray.readUnsignedExpGolombCodedInt(); // log2_diff_max_min_luma_transform_block_size
-    bitArray.readUnsignedExpGolombCodedInt(); // max_transform_hierarchy_depth_inter
-    bitArray.readUnsignedExpGolombCodedInt(); // max_transform_hierarchy_depth_intra
-    // if (scaling_list_enabled_flag) { if (sps_scaling_list_data_present_flag) {...}}
-    boolean scalingListEnabled = bitArray.readBit();
-    if (scalingListEnabled && bitArray.readBit()) {
-      skipScalingList(bitArray);
-    }
-    bitArray.skipBits(2); // amp_enabled_flag (1), sample_adaptive_offset_enabled_flag (1)
-    if (bitArray.readBit()) { // pcm_enabled_flag
-      // pcm_sample_bit_depth_luma_minus1 (4), pcm_sample_bit_depth_chroma_minus1 (4)
-      bitArray.skipBits(8);
-      bitArray.readUnsignedExpGolombCodedInt(); // log2_min_pcm_luma_coding_block_size_minus3
-      bitArray.readUnsignedExpGolombCodedInt(); // log2_diff_max_min_pcm_luma_coding_block_size
-      bitArray.skipBit(); // pcm_loop_filter_disabled_flag
-    }
-    // Skips all short term reference picture sets.
-    skipShortTermRefPicSets(bitArray);
-    if (bitArray.readBit()) { // long_term_ref_pics_present_flag
-      // num_long_term_ref_pics_sps
-      for (int i = 0; i < bitArray.readUnsignedExpGolombCodedInt(); i++) {
-        int ltRefPicPocLsbSpsLength = log2MaxPicOrderCntLsbMinus4 + 4;
-        // lt_ref_pic_poc_lsb_sps[i], used_by_curr_pic_lt_sps_flag[i]
-        bitArray.skipBits(ltRefPicPocLsbSpsLength + 1);
-      }
-    }
-    bitArray.skipBits(2); // sps_temporal_mvp_enabled_flag, strong_intra_smoothing_enabled_flag
-    float pixelWidthHeightRatio = 1;
-    if (bitArray.readBit()) { // vui_parameters_present_flag
-      if (bitArray.readBit()) { // aspect_ratio_info_present_flag
-        int aspectRatioIdc = bitArray.readBits(8);
-        if (aspectRatioIdc == NalUnitUtil.EXTENDED_SAR) {
-          int sarWidth = bitArray.readBits(16);
-          int sarHeight = bitArray.readBits(16);
-          if (sarWidth != 0 && sarHeight != 0) {
-            pixelWidthHeightRatio = (float) sarWidth / sarHeight;
-          }
-        } else if (aspectRatioIdc < NalUnitUtil.ASPECT_RATIO_IDC_VALUES.length) {
-          pixelWidthHeightRatio = NalUnitUtil.ASPECT_RATIO_IDC_VALUES[aspectRatioIdc];
-        } else {
-          Log.w(TAG, "Unexpected aspect_ratio_idc value: " + aspectRatioIdc);
-        }
-      }
-      if (bitArray.readBit()) { // overscan_info_present_flag
-        bitArray.skipBit(); // overscan_appropriate_flag
-      }
-      if (bitArray.readBit()) { // video_signal_type_present_flag
-        bitArray.skipBits(4); // video_format, video_full_range_flag
-        if (bitArray.readBit()) { // colour_description_present_flag
-          // colour_primaries, transfer_characteristics, matrix_coeffs
-          bitArray.skipBits(24);
-        }
-      }
-      if (bitArray.readBit()) { // chroma_loc_info_present_flag
-        bitArray.readUnsignedExpGolombCodedInt(); // chroma_sample_loc_type_top_field
-        bitArray.readUnsignedExpGolombCodedInt(); // chroma_sample_loc_type_bottom_field
-      }
-      bitArray.skipBit(); // neutral_chroma_indication_flag
-      if (bitArray.readBit()) { // field_seq_flag
-        // field_seq_flag equal to 1 indicates that the coded video sequence conveys pictures that
-        // represent fields, which means that frame height is double the picture height.
-        picHeightInLumaSamples *= 2;
-      }
-    }
 
     String codecs =
         CodecSpecificDataUtil.buildHevcCodecString(
-            generalProfileSpace,
+            spsData.generalProfileSpace,
-            generalTierFlag,
+            spsData.generalTierFlag,
-            generalProfileIdc,
+            spsData.generalProfileIdc,
-            generalProfileCompatibilityFlags,
+            spsData.generalProfileCompatibilityFlags,
-            constraintBytes,
+            spsData.constraintBytes,
-            generalLevelIdc);
+            spsData.generalLevelIdc);
 
     return new Format.Builder()
         .setId(formatId)
         .setSampleMimeType(MimeTypes.VIDEO_H265)
         .setCodecs(codecs)
-        .setWidth(picWidthInLumaSamples)
+        .setWidth(spsData.width)
-        .setHeight(picHeightInLumaSamples)
+        .setHeight(spsData.height)
-        .setPixelWidthHeightRatio(pixelWidthHeightRatio)
+        .setPixelWidthHeightRatio(spsData.pixelWidthHeightRatio)
         .setInitializationData(Collections.singletonList(csdData))
         .build();
   }
 
-  /** Skips scaling_list_data(). See H.265/HEVC (2014) 7.3.4. */
-  private static void skipScalingList(ParsableNalUnitBitArray bitArray) {
-    for (int sizeId = 0; sizeId < 4; sizeId++) {
-      for (int matrixId = 0; matrixId < 6; matrixId += sizeId == 3 ? 3 : 1) {
-        if (!bitArray.readBit()) { // scaling_list_pred_mode_flag[sizeId][matrixId]
-          // scaling_list_pred_matrix_id_delta[sizeId][matrixId]
-          bitArray.readUnsignedExpGolombCodedInt();
-        } else {
-          int coefNum = min(64, 1 << (4 + (sizeId << 1)));
-          if (sizeId > 1) {
-            // scaling_list_dc_coef_minus8[sizeId - 2][matrixId]
-            bitArray.readSignedExpGolombCodedInt();
-          }
-          for (int i = 0; i < coefNum; i++) {
-            bitArray.readSignedExpGolombCodedInt(); // scaling_list_delta_coef
-          }
-        }
-      }
-    }
-  }
-
-  /**
-   * Reads the number of short term reference picture sets in a SPS as ue(v), then skips all of
-   * them. See H.265/HEVC (2014) 7.3.7.
-   */
-  private static void skipShortTermRefPicSets(ParsableNalUnitBitArray bitArray) {
-    int numShortTermRefPicSets = bitArray.readUnsignedExpGolombCodedInt();
-    boolean interRefPicSetPredictionFlag = false;
-    int numNegativePics;
-    int numPositivePics;
-    // As this method applies in a SPS, the only element of NumDeltaPocs accessed is the previous
-    // one, so we just keep track of that rather than storing the whole array.
-    // RefRpsIdx = stRpsIdx - (delta_idx_minus1 + 1) and delta_idx_minus1 is always zero in SPS.
-    int previousNumDeltaPocs = 0;
-    for (int stRpsIdx = 0; stRpsIdx < numShortTermRefPicSets; stRpsIdx++) {
-      if (stRpsIdx != 0) {
-        interRefPicSetPredictionFlag = bitArray.readBit();
-      }
-      if (interRefPicSetPredictionFlag) {
-        bitArray.skipBit(); // delta_rps_sign
-        bitArray.readUnsignedExpGolombCodedInt(); // abs_delta_rps_minus1
-        for (int j = 0; j <= previousNumDeltaPocs; j++) {
-          if (bitArray.readBit()) { // used_by_curr_pic_flag[j]
-            bitArray.skipBit(); // use_delta_flag[j]
-          }
-        }
-      } else {
-        numNegativePics = bitArray.readUnsignedExpGolombCodedInt();
-        numPositivePics = bitArray.readUnsignedExpGolombCodedInt();
-        previousNumDeltaPocs = numNegativePics + numPositivePics;
-        for (int i = 0; i < numNegativePics; i++) {
-          bitArray.readUnsignedExpGolombCodedInt(); // delta_poc_s0_minus1[i]
-          bitArray.skipBit(); // used_by_curr_pic_s0_flag[i]
-        }
-        for (int i = 0; i < numPositivePics; i++) {
-          bitArray.readUnsignedExpGolombCodedInt(); // delta_poc_s1_minus1[i]
-          bitArray.skipBit(); // used_by_curr_pic_s1_flag[i]
-        }
-      }
-    }
-  }
-
   @EnsuresNonNull({"output", "sampleReader"})
   private void assertTracksCreated() {
     Assertions.checkStateNotNull(output);

libraries/extractor/src/test/java/androidx/media3/extractor/ts/TsExtractorTest.java

@@ -92,6 +92,12 @@ public final class TsExtractorTest {
     ExtractorAsserts.assertBehavior(TsExtractor::new, "media/ts/sample_h265.ts", simulationConfig);
   }
 
+  @Test
+  public void sampleWithH265RpsPred() throws Exception {
+    ExtractorAsserts.assertBehavior(
+        TsExtractor::new, "media/ts/sample_h265_rps_pred.ts", simulationConfig);
+  }
+
   @Test
   public void sampleWithScte35() throws Exception {
     ExtractorAsserts.assertBehavior(

libraries/test_data/src/test/assets/extractordumps/ts/sample_h265_rps_pred.ts.0.dump

@@ -0,0 +1,81 @@
+seekMap:
+  isSeekable = true
+  duration = 1000000
+  getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
+  getPosition(500000) = [[timeUs=500000, position=7134]]
+  getPosition(1000000) = [[timeUs=1000000, position=14457]]
+numberOfTracks = 1
+track 256:
+  total output bytes = 10004
+  sample count = 15
+  format 0:
+    id = 1/256
+    sampleMimeType = video/hevc
+    codecs = hvc1.1.6.L63.90
+    width = 914
+    height = 686
+    pixelWidthHeightRatio = 1.0003651
+    initializationData:
+      data = length 146, hash 61554FEF
+  sample 0:
+    time = 266666
+    flags = 1
+    data = length 7464, hash EBF8518B
+  sample 1:
+    time = 1200000
+    flags = 0
+    data = length 1042, hash F69C93E1
+  sample 2:
+    time = 733333
+    flags = 0
+    data = length 465, hash 2B469969
+  sample 3:
+    time = 466666
+    flags = 0
+    data = length 177, hash 79777966
+  sample 4:
+    time = 333333
+    flags = 0
+    data = length 65, hash 63DA4886
+  sample 5:
+    time = 400000
+    flags = 0
+    data = length 33, hash EFE759C6
+  sample 6:
+    time = 600000
+    flags = 0
+    data = length 88, hash 98333D02
+  sample 7:
+    time = 533333
+    flags = 0
+    data = length 49, hash F9A023E1
+  sample 8:
+    time = 666666
+    flags = 0
+    data = length 58, hash 74F1E9D9
+  sample 9:
+    time = 933333
+    flags = 0
+    data = length 114, hash FA033C4D
+  sample 10:
+    time = 800000
+    flags = 0
+    data = length 87, hash 1A1C57E4
+  sample 11:
+    time = 866666
+    flags = 0
+    data = length 65, hash 59F937BE
+  sample 12:
+    time = 1066666
+    flags = 0
+    data = length 94, hash 5D02AC81
+  sample 13:
+    time = 1000000
+    flags = 0
+    data = length 57, hash 2750D207
+  sample 14:
+    time = 1133333
+    flags = 0
+    data = length 46, hash CE770A40
+tracksEnded = true

libraries/test_data/src/test/assets/extractordumps/ts/sample_h265_rps_pred.ts.1.dump

@@ -0,0 +1,65 @@
+seekMap:
+  isSeekable = true
+  duration = 1000000
+  getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
+  getPosition(500000) = [[timeUs=500000, position=7134]]
+  getPosition(1000000) = [[timeUs=1000000, position=14457]]
+numberOfTracks = 1
+track 256:
+  total output bytes = 856
+  sample count = 11
+  format 0:
+    id = 1/256
+    sampleMimeType = video/hevc
+    codecs = hvc1.1.6.L63.90
+    width = 914
+    height = 686
+    pixelWidthHeightRatio = 1.0003651
+    initializationData:
+      data = length 146, hash 61554FEF
+  sample 0:
+    time = 333333
+    flags = 0
+    data = length 65, hash 63DA4886
+  sample 1:
+    time = 400000
+    flags = 0
+    data = length 33, hash EFE759C6
+  sample 2:
+    time = 600000
+    flags = 0
+    data = length 88, hash 98333D02
+  sample 3:
+    time = 533333
+    flags = 0
+    data = length 49, hash F9A023E1
+  sample 4:
+    time = 666666
+    flags = 0
+    data = length 58, hash 74F1E9D9
+  sample 5:
+    time = 933333
+    flags = 0
+    data = length 114, hash FA033C4D
+  sample 6:
+    time = 800000
+    flags = 0
+    data = length 87, hash 1A1C57E4
+  sample 7:
+    time = 866666
+    flags = 0
+    data = length 65, hash 59F937BE
+  sample 8:
+    time = 1066666
+    flags = 0
+    data = length 94, hash 5D02AC81
+  sample 9:
+    time = 1000000
+    flags = 0
+    data = length 57, hash 2750D207
+  sample 10:
+    time = 1133333
+    flags = 0
+    data = length 46, hash CE770A40
+tracksEnded = true

libraries/test_data/src/test/assets/extractordumps/ts/sample_h265_rps_pred.ts.2.dump

@@ -0,0 +1,45 @@
+seekMap:
+  isSeekable = true
+  duration = 1000000
+  getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
+  getPosition(500000) = [[timeUs=500000, position=7134]]
+  getPosition(1000000) = [[timeUs=1000000, position=14457]]
+numberOfTracks = 1
+track 256:
+  total output bytes = 563
+  sample count = 6
+  format 0:
+    id = 1/256
+    sampleMimeType = video/hevc
+    codecs = hvc1.1.6.L63.90
+    width = 914
+    height = 686
+    pixelWidthHeightRatio = 1.0003651
+    initializationData:
+      data = length 146, hash 61554FEF
+  sample 0:
+    time = 933333
+    flags = 0
+    data = length 114, hash FA033C4D
+  sample 1:
+    time = 800000
+    flags = 0
+    data = length 87, hash 1A1C57E4
+  sample 2:
+    time = 866666
+    flags = 0
+    data = length 65, hash 59F937BE
+  sample 3:
+    time = 1066666
+    flags = 0
+    data = length 94, hash 5D02AC81
+  sample 4:
+    time = 1000000
+    flags = 0
+    data = length 57, hash 2750D207
+  sample 5:
+    time = 1133333
+    flags = 0
+    data = length 46, hash CE770A40
+tracksEnded = true

libraries/test_data/src/test/assets/extractordumps/ts/sample_h265_rps_pred.ts.3.dump

@@ -0,0 +1,25 @@
+seekMap:
+  isSeekable = true
+  duration = 1000000
+  getPosition(0) = [[timeUs=0, position=0]]
+  getPosition(1) = [[timeUs=1, position=0]]
+  getPosition(500000) = [[timeUs=500000, position=7134]]
+  getPosition(1000000) = [[timeUs=1000000, position=14457]]
+numberOfTracks = 1
+track 256:
+  total output bytes = 146
+  sample count = 1
+  format 0:
+    id = 1/256
+    sampleMimeType = video/hevc
+    codecs = hvc1.1.6.L63.90
+    width = 914
+    height = 686
+    pixelWidthHeightRatio = 1.0003651
+    initializationData:
+      data = length 146, hash 61554FEF
+  sample 0:
+    time = 1133333
+    flags = 0
+    data = length 46, hash CE770A40
+tracksEnded = true

libraries/test_data/src/test/assets/extractordumps/ts/sample_h265_rps_pred.ts.unknown_length.dump

@@ -0,0 +1,78 @@
+seekMap:
+  isSeekable = false
+  duration = UNSET TIME
+  getPosition(0) = [[timeUs=0, position=0]]
+numberOfTracks = 1
+track 256:
+  total output bytes = 10004
+  sample count = 15
+  format 0:
+    id = 1/256
+    sampleMimeType = video/hevc
+    codecs = hvc1.1.6.L63.90
+    width = 914
+    height = 686
+    pixelWidthHeightRatio = 1.0003651
+    initializationData:
+      data = length 146, hash 61554FEF
+  sample 0:
+    time = 266666
+    flags = 1
+    data = length 7464, hash EBF8518B
+  sample 1:
+    time = 1200000
+    flags = 0
+    data = length 1042, hash F69C93E1
+  sample 2:
+    time = 733333
+    flags = 0
+    data = length 465, hash 2B469969
+  sample 3:
+    time = 466666
+    flags = 0
+    data = length 177, hash 79777966
+  sample 4:
+    time = 333333
+    flags = 0
+    data = length 65, hash 63DA4886
+  sample 5:
+    time = 400000
+    flags = 0
+    data = length 33, hash EFE759C6
+  sample 6:
+    time = 600000
+    flags = 0
+    data = length 88, hash 98333D02
+  sample 7:
+    time = 533333
+    flags = 0
+    data = length 49, hash F9A023E1
+  sample 8:
+    time = 666666
+    flags = 0
+    data = length 58, hash 74F1E9D9
+  sample 9:
+    time = 933333
+    flags = 0
+    data = length 114, hash FA033C4D
+  sample 10:
+    time = 800000
+    flags = 0
+    data = length 87, hash 1A1C57E4
+  sample 11:
+    time = 866666
+    flags = 0
+    data = length 65, hash 59F937BE
+  sample 12:
+    time = 1066666
+    flags = 0
+    data = length 94, hash 5D02AC81
+  sample 13:
+    time = 1000000
+    flags = 0
+    data = length 57, hash 2750D207
+  sample 14:
+    time = 1133333
+    flags = 0
+    data = length 46, hash CE770A40
+tracksEnded = true